I use my 28mm Olfa ergonomic cutter way more than my 45mm. I like the way it fits in my hand better than the larger one so I have less hand fatigue when doing a lot of cutting. I haven't really noticed if the blade gets dull faster than my 45mm but I'm one who has to be vigilant about not pushing too hard or I'll dull any blade faster as well as putting deep cuts in my mat. I really have to pay attention to that.
Cari