Here are my thoughts. The R3M has been proven to be a more reliable gun than the impact, and its barrel seems to be better than smooth twist at closer ranges. (I'm only stating this since a couple of big channels have listed other guns with traditional rifling as their best 25m gun, despite owning impacts or another FX gun.) If you're not going to be pushing 75+ yards regularly, the impact isn't going to be much more accurate. Does it still have some attractive features? Yes. However, It all comes down to your individual needs for what the gun will need to do.
If you need multiple bottles, prefer a bullpup's compactness, may need to switch calibers for different game, and take 150-yard shots, then the impact is hard to beat. If you rarely venture beyond 75 yards, have never emptied your reservoir on a hunt, don't see your routine changing up (e.g. switching calibers), and your gun hits the bullseye, I don't see a reason to get rid of the R3M from a practical standpoint.
The reason I chose not to buy one was because I wanted something to build on, that I would only take apart when I was improving something, not fixing it. I wanted to get something with a theme that stops the shot clock of everyday life and gets people interested in the sport. Any well-tuned PCP can do this, but I chose to buy and modify a Marauder because it shows that even entry-level guns can compete with the best when time, money, and heart are put into them.
Can you link one of the compressors you're talking about? All the one's I've seen go for at least a few thousand.
