I've used both the "old" can/nozzle and the "new" nozzle Rustoleums. I prefer the control and lower flow rate of the old version. As regards clogs, it has always been an issue as far as I'm concerned, so when I'm done, I always remove the nozzle and soak it in mineral spirits, then blow it out. I never measured just how big the hole was, but I use leftover Mouse race line clippings (.010 solids) to poke the holes in both directions. The hole is actually bigger, I believe. I also swab out the top of the can with the nozzle removed using mineral spirits and store it that way. Having a glump of dried paint break loose when you reinstall the nozzle seems like a good way to achieve the problem you described? There may be better techniques, and I don't claim to be a painter.
I really like their Maui Blue, though....