Congrats on your new Marauder. I'll be eagerly looking forward to your review.
I read on another forum that the .25 Mrods are factory set for a 3000 psi fill and no doubt they set it at the max psi so it can push the larger 25 cal pellets with authority. That doesn't mean however that you can't use a lower fill pressure, you certainly can if you want to..... and since you're going to be hand pumping it I think you will indeed want to shoot at a lower pressure. Hand pumping using a 2000 psi isn't to bad but when you try going from 2000 to 3000 with a hand pump it becomes a bit of work and definitely not something you'll enjoy..... I was doing some chrony work with my Air Force Condor this afternoon and after a long shot string I decided to use one of my hand pumps to air it back up to 2800 psi since I hadn't used my hand pumps for quite a while.... well,,,,, I got it aired back up to 2800 again and I was glad to see my pump is still working fine, but I can also tell you I won't be using the hand pump to do that again any time soon !!!!
I have no idea what kind of fps you'll get with a lower fill pressure as I don't own a 25 Mrod and the few reviews I've read on the rifle have all been with shooters using the max fill pressure.
Anyway, congrats and I'll be looking forward to your review...
Jeff