I can wholeheartedly concur Andriko, I'm struggling, a little at least, with adjusting the open draw using my 9mm filter pipes (I have two) with no filter or adapter...and you're right, my pipe(s) are getting hot too.On the few occasions I've smoked a 9mm pipe with no filter or adaptor, I found the draw too damn big, and the tobacco would over heat too much, made worse by the fact I draw a bit too hard at the best of times. I do have an adapter, but have never used it as I find the filter works quite well with a lot of the pipes and tobaccos I smoke.
My only advice of smoking a gaping 9mm without anything in there would be to watch out for tongue bite. Cleaning the adapter might be a pain, but how much of a pain is taking tacking it out and running it under water for a few seconds?
Gonna try the recently received 9mm adapter tonight in my Peterson 'Derry' - looking forward to discovering a positive difference