I sold my XVR over a year ago do to 77year old joints. I am surprised no one is talking about how effective the round is on game, in my case pigs. We are talking instant "bang flops".
I would not change the spring. I believe that cycling the action (lots of rounds down range) will do more to lighten things up than locking the slide back. It's a physics thing.:)
Spent some time with my MP9 Pro 5" yesterday. It wears a Leupold Delta Point Pro. 100 rounds down range, at thirty yards all hit a 4" steel target. Getting smoother with each outing.:)
A year ago when I could not find powder I acquired 10 lbs of Autocomp. Works very well in the 45 ACP and looks good for heavier loads in 38 Spec. A bit bulkier, meters well.