Feel your frustration. P1000 going on three years old, most aftermarket manufacturers don't want to drop a ton of r&d money. I also wonder if the ones that have put their toe in the water have experienced clutch problems on added horsepower? I've dealt with the boys at fuelmoto with motorcycles, I bet they can answer that. Makes it hard to sell when they know the customers machine might not be up for the add on. With the internet bad reviews travel fast.
Being in central Illinois most of my riding has been country roads(paved). Our fields still have crops in them so running a water way or two bout it for now, each day that's changing. For that purpose p1000 works great. Only thing I'd change would be tires. Bighorns aren't pavement friendly, noisy and wearing on lug bars.
Two weeks ago I got the chance to take it to upper Wisconsin/U.P. to ride trail systems there. I got one good day of riding in (bout 100 miles) half day was with 3 adult males. I realize Wisconsin is not Utah bit more flat but gave me a chance to observe something other then paved roads. The trails have a higher sand(silicon) base to soil than my home. Upper Wisconsin also had 3 days of rain before I got there, no dust at all. My machine was about flawless in these conditions. The bighorn tires came into their own. Trails were due for grooming plenty of standing water. Lots of this riding reminded me of the low whoops section in a motocross track. Guys that ride snowmobiles understand this stuff the stop and go again stuff that needs groomed out. Two guys I took with me had the same observation, man this thing rides awesome. One of the guys was a farm boy that been riding atv's since he could throw a leg over. It rode great most of the travel speed was 25-35mph. Speed limit UTV's 35. In the corners tried to keep it there. Ran tires at 14psi higher then recommended didn't want to blow off bead, cell service(no service) in area. The only thing I noticed when pushing hard in a turn the front pushes out (understeer). Maybe this can be corrected with tire pressure/new tires. Another thing I've not seen this posted anywhere probably due to variances but I was getting right at 20mpg. As you can tell I was way more impressed with it over my paved road riding at home. It just didn't have any real bad habits and steering was predictable and ride was outstanding. I didn't think the stock shocks on a 5-D with 750lbs of guys would cut it, they did on these trails.
Ive rode ATV's in sand hills and the one thing you never have enough in sand in HP. Tire spin is king in most of that riding and I can see that P1000 doesn't excel at that. If most of your riding or half of your riding is sand I'd be in a sport model. I needed a utilitarian machine so the General deluxe was on my short list. Seats are outstanding in the Polaris but dam they are proud of it. Dealer was going to drop 1500 off msrp on a '17. Two seater just wasn't gonna cut it for me and the crew cab, didn't want a school bus. I do think if performance upgrades=max hp is your want, a turbo be in your future.
I'd be curious to see what a trade in value on a 5-D would be. At first I regretted not getting the General but the more miles I put on this the more it's impressed me.
Good luck with your decision.
Hawkeye