I turned up the fuel pump on my LS U5020C (Mitsubishi engine) last March and don't regret it for a second. The improved responsiveness and lack of engine lack is very noticeable. It allows me to do the same work in a higher gear and less rpm.
Have you considered a skid steer loader? It seems from your post that it may suit the work you do a little better and with impliments run via hydraulics.
Actually, a tracked SS is on my future acquisition list for my business, so I can get a little heavier into lot clearing. Something like a Cat 277c, or ASV100, etc. But for now, all of my implements are 3pt driven, and they do the jobs effectively enough for now.
My goal is to have a SCUT tlb, my midsize HST CUT, and the tracked SS. But for this one more year, I'll just have the CUT. Only occasionally, when stump grinding or heavy grading, could I use more HP. Of course, I could always use a tad more loader lift, mainly just when moving pallets, but my loader warranty will be up next month so I may look into adjusting that a touch.
So anyhow, I'm just trying to figure out if it would be worth it to jump up to the 3 liter engine over my 2.2 liter, if that 3 liter could be tuned to run at 60 horse like it is in the 1660. That would be a 25 percent jump in HP from my 1648, which would probably equate to about 8-10 hp at the PTO.
Lol, these are just off season thoughts for the winter time!