The Pro Taper EVO is has a 1 mm. thinner wall section. If I were buying a bar for a dirtbike I would look at the EVO. However going on a quad I don't see that it's worth the extra money over a Pro Taper Contour bar.
Pro Taper does make VERY good handlebars. I've had them on just about every dirtbike I've ever owned. I'm getting ready to put a set on my Raptor.
I've got the PRO_TAPER SE on mine and I love them. Alot lighter also, the stockers are HEAVY. Any thing other then the RAPTOR BEND will hit your tank, unless you use a riser. I've got the MID BEND on mine and just added a 3/4" riser and they fit me perfect.