I looked and these threads are bimodal: they either discuss more expensive solutions (e.g. taipans, pulsar, redwolf) or more entry-level solutions (e.g. prod or mrod), never both. That is, if I have a bolt action mrod and a pulsar next to each other, will I hear a difference in perceived noise level at 10yds away? Are they both as accurate at 50yds?
What you're asking is very subjective. I don't own either of those 2 airguns so I can't give my opinion on it. I also don't own a Taipan Veteran yet so no luck there as well. I think someone who's owned all the guns you mentioned could give a better opinion. What I do know is very general. Make a list of priorities in what you want in an airgun and go from there. JungleShooter is on the right track.
Decide on a caliber. In general, .177 will be quieter than .22. .22 will be quieter than .25 and so on. Pick a platform. Bullpup or rifle? With a bullpup, the shooter will hear more of the mechanics of the gun because the hammer, valve, and regulator is right under the person's ear. The Pulsar might be the exception. With short guns in general, the barrel is also closer to the shooter's ear compared to a rifle giving the perception that one is louder or quieter than the other.
In terms of power, they should all be compared at the same speeds in FPS and caliber. In terms of accuracy, I consider a .22 shooting a five shot group under 1/2 inch at 50 yards in good weather conditions very acceptable. Some say their Mrods can do this. Most Daystates with Lothar Walther (LW) barrels should be able to do this. Either brand can do it or better if they win the barrel lottery.
Another thing to consider is barrel length. The shorter the barrel, the louder it will be in general. A higher regulator and hammer spring tension (HST) would need to be increased to bring it up to the appropriate speed and FPE levels. With a longer barrel and larger plenum reservoir, it's the other way around. Less stress/tension on the internals making it a quieter airgun.
When testing for quietness, it's probably better if you have someone else shoot the gun with you standing a distance away. There are other variables to consider. There are some moderators that might improve accuracy or ruin it. Even FPS can be increased or decreased with different moderators. Some are designed more as an air stripper than a silencer. Some are designed to work as a whole system with the shroud. In the end, you might just end up with a whole collection of moderators like most of us just to try on every airgun you get to find the right one.
Sorry I couldn't give you a more direct answer.
You're hunting for the "quietest, shortest, 25+FPE PCP" — and those criteria are similar to what I look for in a PCP.
This is when you reach airgun nirvana bliss lol.
