Back when I used to wear pull-on style boots, (Ok, they were cowboy boots, shoot me.) the guys I bought from always said your toes should be stationary, but the heel will slide a bit.

Not an expert, but I would guess they should fit that way.

I bought that same style boot about 4 years ago from Wal-Mart. I did not break them in before Pennsic and ended up fighting with my feet in duct tape because of the blisters. The shoes never did break in. I always got blisters on my heel when fighting in them. That was just my experience. Now I stick with lace up boots.

I've got a set of engineer type (biker) boots that I wear often. I've managed to keep them clean enough I can wear them as dress work boots in the office. I've not fought in them yet though. Yes, Slip on boots your heel will slide a bit. Up and down a little is acceptable. Side to side and you may be looking at injuries eventually. Honestly if you want to fight safe, tie them on is my theory. Keep in mind I'm a noob fighter too. I authorized finally last weekend. My recommendation comes from seeing downhill skiing injuries from loose boots. Totally differint sport though. Too tight is not good either as it cuts off circualtion and makes you feet cold. Oh wait that is skiing related and not really fighting is it?