I happen to have an LTR450 and raptor 660, and I can say no matter what you'll tinker with it if you like mods. long travel will be one of the most expensive things alot of guys add. power only costs that much when you go big like big bore, stroker porting cams, the works... I'd just keep the 2 stroke. I'm considering getting a blaster since they're so cheap to get parts for lol. if I got a 450 again, the honda would be at the top of my list as the new ones have reverse and parts are easier to come by.
If my 250r comes out as good as I hope I'm probably gonna get rid of my LTR actually lol. and either race ride MX on the 250r or trail/mud the 660. may end up MXing the raptor if/when the 250r is down...
reliability = maintenance like said. I'm constantly putting money into fixing my 4 strokes things break /story lol. oil changes get expensive, I have two bikes I'm constantly changing oil, both bikes cost me $30-40 per oil change. you do it pretty much every 2 rides..