I would say that since I have a Magic Mouse from Apple, I'm more worried about my scroll finger wearing out before my scroll "wheel." However, I gotta say, I wasn't a big fan of infinite scroll when google introduced it to it's search results, but I WAS a fan when they implemented the functionality on their image search. It makes sense to have it on image search, because you are quickly glancing over images, looking for the one you want, but search results (or blog posts for that matter) require a little more attention, and it isn't really appropriate for those situations. However, I have heard that some people enjoy, so if I were to implement it, I would default to traditional pagination, but have the option for the user to enable the infinite scroll if they so desired.