I have been rolling the dice, no cover, 950 miles on mine so far so good. I would do the upgrade but I don't want to loose the ADC. Seems like I'm one of the few who like using it. That being said, 95% of my riding is trail riding so I rarely need to use 4wd except for steep hill climbs and creek crossings.
I think alot depends on your riding style. Will you be putting it in deep mud, technical rock climbing? In both of those cases I would replace the cover if it were me.
2013 Sportsman 850 XP HO EPS, 28" Kenda Bearclaw HTRs, Elka Stage 2, ATV-Guru bumper w/ LED light bar, JCCapri bushings, Cecco F+R braces, Uni air filter, NGK plugs, ODI Rogue grips
SOLD 2003 Sportsman 700 Twin, 26" Mud Lite XTRs
SOLD 2000 Honda Rancher 350 ES, 26" Outlaws
Kawasaki Bayou 220
Honda ATC 3 Wheeler