I've only run Deca so I can't speak from experience but NPP does cause leaner gains and less bloating than Deca. When I asked why a fellow GrAnabolic rep from another board had this to say. This is copy and pasted...
little background on NPP and why it bloats less.
We often hear of people running "deca", but I consider this to be a misnomer. What we are actually talking about is Nandrolone. Deca is simply an abbreviation for Decanoate which is the Ester. The name "Deca" comes from a product created by Organon called Decca Durabolin hence the nickname "Deca". Decanoate or Phenyl Prop are the Esters we will find with Nandrolone. More on that later.
Nandrolone is a NOR 19 compound, which is a modified testosterone hormone with the carbon atom removed at the 19th position. Nandrolone has an anabolic to androgenic ratio of 125:37. This means we get a very good anabolic boost with a moderate androgenic property. There is a low aromatizing property to nandrolone, it converts to estrogen at only about 20%, as much as Testosterone. So Estrogen control should be quite easy with a standard dose of the Ai. of your choice.
A Benefit of Nandrolone is the versatility, allowing it to be used for both cutting or bulking cycles. Phenylprop would typically be the choice for cutting, though. A very well known effect from Nandrolone is it's ability to relive joint pain. I can attest to this first hand as i have found great relief from arthritic joint pain by using Nandrolone. Be warned, however, this relief is not part of a permanent repair to joint tissue. Although some research does claim that Nandrolone stimulates collagen production and increases IGF production. Red blood cell production also increases which decreases muscle catabolism, increases endurances by bringing more oxygen to muscle cells , and clears lactic acid quicker. A study with post menopausal women showed nandrolone to be effective treatment against osteoporosis and anemia. Through my own blood tests I can confirm a significant increase to blood iron levels.
Reportedly side effects can be insomnia, nausea and diarrhea, although I have never experiences any of these from nandrolones. Much more common side effects are water retention, testicular atrophy and impotence, A.K.A. "Deca Dick". None of these side effect should be taken lightly, however these are generally very manageable if you understand where they are coming from.
Nandrolones cause the slow down of endogenous testosterone, hence the reason you always supplement with testosterone. Generally speaking, testosterone should be run at twice the dosage of Deca or Npp. This is also a progestenic steroid, causing an increase in progesterone. This contributes to ? HPTA shut down and testicular atrophy. This can be counteracted with the use of HCG which acts as LH would and stimulates the testes. Increased progesterone also causes a rise in prolactin. This is the substance produced in the body after orgasm, creating a feeling of being satisfied. You can see how this would reduce libido greatly. Cabergoline or Bromocriptine will take care of excess prolactin easily .
When Nandrolone is used with the decanoate ester it has a very long half life of 15 days. Making once weekly injections is sufficient. Phenylprop half life is much shorter at 5 days, making it possible to run NPP on a 4 day schedule. At day 5 with Npp a severe drop off of plasma levels is seen. An interesting point to note is that higher blood plasma levels are found when gluteal injections are used over deltoids. Although the half life is quite long, detection in the system is much longer. In fact, Nandrolone Deca can be detected up to 18 months from usage.

NPP and Nandralone Deca releases almost the same amount of hormone per 100 mg. 69 and 65% respectively. Yet a distinct difference between the two is water retention and being much less on NPP. NPP is often credited for giving cleaner gains. Also because of it's short active life any sides that become more of an issue than expected , will be alleviated quite quickly.
Gains from Nandro is generally slow and steady, although use of NPP as a kick start will accelerate things a bit. Deca or Npp cycles should be run for a minmimum of 12 weeks, with 16 being optimal and 18 being no problem at all. About two weeks after the cycle has ended an aggressive P.C.T. of Nolva , Clomid and Hcg must be used, due to the highly suppressive nature of the compound.
So, for a quick summary, Decca for joint therapy can be as low as 100mg week, but to witness real gains the dosage will need to be more like 400-600 mg a week. You may run your Npp on a 2-4 day injection schedule and your ND on a 4 day to 1 week schedule.
Remember your test and make 2:1 your starting point. Poor sexual performance would require increasing beyond that ratio. have your progesterone drugs on hand in addition to normal A.I as you will most certainly need to regulate progesterone/prolactin issues.
With this information and shared knowledge you should certainly be able to prepare for and run one of the best compounds on the market today, Nandrolone Decanoate or Nandrolone Phenylprop .
Effects of nandrolone decanoate therapy on bone mass and calcium metabolism
in women with established post-menopausal osteoporosis: a double-blind
placebo-controlled study.Gennari C, AgnusDei D, Gonnelli S, Nardi P.Maturitas.
so when We're talking about a short esters,and how the ester works?
Lets brake this down in long ester terms with ester build up.. a great illustration to give here is the overall amount of ester being used at any given time..concerning the active ester!
Prop ester,giving the fact that's a propionic acid ester, its lesser in weight,thus its in a smaller ester chain, it will mobilize faster, leading to less build up.. clearing faster..Now consider using a heaver weight ester (enth/cyp), this ester tends to create a significant build up faster than it can actually metabolize,providing the user at any giving time a steady supply of a high concentration at any given moment..keep in mind here guys, when utilizing a shorter ester that clears faster and skips the build up phase known as the ( partition co-efficient effect ).. heavier the ester, greater the build up ( basics) and a larger release over time.. The shorter ester works in the same respects as a long ester and similar manner,however with respect to release in the blood, and what's actually bio-available.. a side note..The enzymes called hydrolysate is responsible for braking down the ester from the testosterone molecule and dictating what ester is to be more active in the blood.. thus. the prop is what we call ( in and out ).. It doesn't allow the body to convert or have the test ester manipulated and concerted into estro..Thus leading to less water retention.. You actually utilizing more test, with less estro effects.. when pure test doesn't have any conversion,or e2/ stimulation..the effects are leaner, and more quality..