Okay, Steve, so although I tested my 1RM with pronated pulls I can still switch-it-up and should still see an increase in my 1RM in about 3-4 weeks?
Maybe yes, maybe no - some people's 1RM goes up when their endurance goes up, others don't find that and their 1RM might even go down.
As to switching the grip, you kind of have to go by feel here. If doing all pullup grip works for you, then fine, since that's what you're training to improve, stick with it. I, and many others, find it very easy to overdo pullups, so switching the grip is easy to integrate into a training program, e.g., for me, when working on 1RM pullups, I will often alternate sets of over- and under-hand grip - I still get plenty of pullup grip practice. Another approach I've used is that, as fatigue sets in, rather than reducing weight and/or volume, I switch to a chinup grip since I'm stronger that way. But again here, this is highly personal, e.g., some people are equally strong with both grips, some (although not many) are stronger with a pullup grip than with a chinup grip. And some people find the chinup grip bothers their shoulders; other people find it the other way.
So, no one, simple answer, sorry.
-S-