I think that the amount of rounding is probably equivalent, and not terrible, in both cases. You just shot one from an angle that makes it easier to see your back. You have a tendency to put the bar ahead of the midfoot by pushing forward with your shins as you drop your butt too low. This causes you to pull the bar around your knees a little. I like pulling in shoes and recommend that my trainees do the same. Yes, you have a slight deficit off the floor, but there are some other benefits that make up for it. Pulling in Chucks provides approximately the same lift over the midfoot, but provides none of the stability WL shoes do.
I don't like that your deads cause back pain for days afterwards. The only things I can tell you are to fix your setup a little and work hard to hold your back blat off the ground. I don't see anything here that is deeply worrisome from an injury perspective, however. Perhaps someone else will see something I missed. I am becoming senile, after all.