What is more important, assuming that you're not planning on replacing the old countertop, is the comparison of the size of the actual cutouts. A top mount sink that's 33 x 19 is going to have a smaller cutout. If you are measuring to the inside of the Hudee (sp?) rim, it sounds as if the hole in the countertop may be too large for a standard sink.
As far as durability, I'd think that the SS would be a little more forgiving of having a frying pan dropped in it - plus you can polish them to remove scratches if necessary, dents not so much. A 20 ga sink has .037" material, a 220 ga is .031" - if you're worried about durability, Kohler makes some nice sinks in 18 ga stainless 33" x 22" so it may have a cutout larger than the old sink - and 18 ga stainless at ,050" is considerable thicker - list price is $895. I have a 25 year old Kohler in the kitchen, and feel that the extra cost was well worth it. What a coincidence, my wife yesterday started a conversation with, "How hard is it to take out the old countertop?" - she also is looking at quartz, and I'm thinking that she'll consider the old sink too shabby to reuse with a shiny new top.