I have mostly been up the MR, not the regular trail. I find it is hard on my shoes, especially carrying a backpack. I use lightweight full leather waterproof high tops. Sometimes even gaitors, since lots of rocks get in my shoes above Iceberg lake. Last time I was there I stopped three times to dump rocks out of my shoes, even with my hightops (not gaitors).
Once I use some $40 high tech lightweight shoes, which actually split apart above Iceberg lake. Since then I try to use a little stronger shoes. I have friends who have done the whole MR in the summer with high top tennis shoes.