Another perspective,
91 indy 500 5500 miles - 1 motor
92 RXL 650 2900 miles no problems
93 wildcat POS
96 Ultra 4000 miles - 1 piston, (piped)
98 Indy 600 3-4000 miles - no problems
2000 Hi-mark 700 2000 ish miles - 2 motors ( once crank seal , then piston and jugs)
2001 RMK 800 4000 miles ish - twin pipes - no problems
2004 Rev 800, 3-4000 miles- 2 motors ( crank seal first time,top end second)
2006 Apex 1000 miles with NOS, 2000 miles boosted - 1 motor (dealer paid)
2009 M8 3000 ish miles- 1 motor (squeaked at about 500 miles)
Bought a used 2008 XP for wife 1400 miles- crank seal went out $4000 grand later (hate XP's great trail sled for wife)
2011 Pro 800 3200 miles - no problems ( installed new pistons and rings cause i sold to a friend)
2013 Pro 800 - 550 miles, no problems (drive shaft clamp, original belt)
So the way I see it, they all have their issues.
Biggest POS's in my opinion, 2008-2010 Dragons and 2007 Rev XRS and 2005-6 Doo 1000's.