Actually very happy with the 9200 running envelopes so far. However on caveat is, the envelopes with the diagonal cut flaps didn't seem to run as well however we had to run some #10 Window and got the square cut flap and ran 10000 really with no issue. We had a Xante and tbh it really was kind of a pain and decided to get rid of it.
I have tried running envelopes on a 7100 and seem to run okay but that was pre-opened flap and did jam every now and again. Ran catalog envelopes and seem to do much better but had to be more conscious of the seem of the envelope as far as where the image was being laid down.