Interesting question.
I don't think it's that much more challenging to perform wearing earplugs, unless they obscure the sound of the music to the extent that I can't hear what's happening onstage. When that happens, it causes me to strain to hear and takes me out of the moment. The main reason I wear earplugs is to protect my hearing.
When I play a drumset for a few minutes without earplugs, even at a moderately medium-quiet volume, I can feel slight pain in my ears; when I play drums with earplugs in, I experience little-to-no hearing pain. I prefer to keep my hearing intact as much as I can.
I've been using the
Etymotic/ACS-type custom fitted ear plugs for years, and it's one of the best investments I've yet made. I never leave home without a pair and definitely recommend them to all musicians, concert-goers, or even anyone who wants to experience more peace and quiet.
If the 3 types of attenuating filters available with the Musicians Earplugs - 9db, 15db, and 25db - I have the 9db and 15db, and the overall effect is like turning down the sound on a radio. The different filters attenuate noise in different ways, as shown on the chart near the bottom of the above link.* The 15 db filters make music sound warm and more visceral feeling, and I find them pleasing to wear when playing drums. These days, I mostly use the 9db filters unless playing at a level that would leave my ears ringing after using them, in which case I use the 15db filters.
I also recently tried the standard fit
ER20 series plugs, which cost substantially less than the Musician's plugs. I recently compared the ER20 and musician's plugs briefly: the ER20 sound similar to the effect of the Musicians Earplugs, but the ER20 feel more scratchy physically and less comfortable than the custom plugs, which I often forget I'm wearing after a musical performance.