I do like that it closes the end of the bar, I was worried about that at first but quickly found that I started riding more like the almighty Burandt says we should all ride with our hands on each grip at all times....everyone has there own style. All in all they are great for smashing through tight trees without busting your hands up or hitting the brake at the wrong time, they are great on the cold trail rides, they are fantastic when rolling your sled over....even in june snow....I love them and come to think of it they help keep your hands on the grips when you are doing a little "push-pull" on the bars type riding. The only drawback I can think of is for those that take to the air big time (you and me both know I am good and safe here) there is the chance of your hand slipping and getting caught in between the bars, I havn't seen any accidents with it but I can imagine.....but for how I ride they are perfect.
I took down a 4" diameter quaky last winter with my left hand guard no problem....they are very rigid!
BTW who did your vents?