Can't beat the XXR for reliability. Rode the hell out of mine and it liked it. However, adding a fan is a good idea (I boiled over plenty in the slow stuff in the heat). Hell, adding a fan to anything that doesn't have one is a good idea in my opinion. Kick starting the pig with cracked ribs or a separated shoulder sucks. When I switched to KTM, I was never happier, and I loved my BRP (my 505 KTM is snappier, lighter, has the magic button, better handling, balance, but it ain't no DS). The Beta DS bikes, in my opinion, are not as good as their KTM counterparts. I like the looks, feel, fit and finish, but many complain about leaking shock seals and other Beta-specific components. KTM is not without its shortcomings too, but those can usually be overcome with aftermarket fixes.
Having owned or ridden a number of thumpers, if I was in the market, I'd be looking for a 450/530 EXC or a Husaberg. If you are dead set on the Pig, then the must-dos include a foot peg mod (I can't remember if right or left, but you'll figure it out), a Vapor computer, a fan and a bigger tank (I went with a Clarke 4.3 and it worked out perfectly). Stock seat kinda sucks, but don't they all. If planning on putting any weight out back, you may need to consider beefing up the sub frame. Rear axle/chain adjustment bolts tend to freeze on these, so drill, tap and install inserts if that happens. You've got to address the front forks (I guess by now the oil should have been changed out, but they came with "whale snot" in them from the factory. I left my stack alone, but went with a very light oil and the biggest Race Tech springs that I could get away with without a revalve and that greatly improved the front end). For the rear, I went with the largest Eibach spring I could get away with without a revalve. The setup worked well for me. Unfortunately, I can't remember those spring sizes, but you'll be able to figure it out from others' posts on the subject. Probably my favorite thing about the Pig was the set-it-and-forget-it valve adjustment. Those suckers always stayed in spec. However, even if you have to adjust the valves, its an old school screwdriver and feeler gauge kinda deal. Since Pigs are getting a bit long in the tooth these days, be prepared to replace the swingarm bearings (special tool) and rear shock linkage bearings. Oh, I also used a CR High Bend bar that helped a lot (the factory handle bar is a horrible size and shap, in my opinion). The stock stator is pretty weak, so an aftermarket stator is a good idea. My guess is if you find the one you like, there's a good chance much of this stuff will have been addressed.
Oh, yea, you've got to uncork it and jet accordingly (like mentioned above, pretty slim chance you'll find one without this procedure already in place).
