Pretty simple
Ripsaw = great on hardpack and wet heavy snow
cobra = better off trail, in loose, fluffy or sandy snow. due to lug design, check out tracksusa.com for pics of the lugs.
personally i'd say the ripsaw is better on trail but the cobra is not a bad trail track at all, if you plan to ride off trail at all, go cobra getting stuck once you will wish you had it.
If you stick to trails or lakes and are a touring rider then I'd say ripsaw. both are very good.
hyfax wear should be the same for both, I've had a ripsaw run through hifax in 600 miles and a buddy did the same to his 1.3 cobra. All depends on the trail conditions you ride on, 50 miles of dirt can kill hyfax in very short amount of time.