I've done it several times with a couple of different G26s. I usually place in the top 20%-25% with a G19/G17, and often break into the top 3 shooters with my G34. Using a G26, I'll usually be found in the top third of all shooters, or slightly lower, depending on how many longer shots there are in the match. It's a great way to really get to know your carry gun under slightly stressful conditions, and a fantastic confidence-builder if you do well with it.
Last year, I picked-up a minty used Gen4 G26 in an unexpected trade on the last day of a gun show, and I had been planning to shoot a local IDPA match that evening. I said what the heck, went home and cleaned the new-to-me Glock, gave it a quick inspection, dripped some lube on it, gathered my gear and headed to the range.
After arriving, we were loading mags in preparation for the first few stages, and the guy next to me sees me loading the short G26 mags, and figures he'll strike up a conversation. "Shooting a G26 tonight, huh? How's it shoot?"
"I don't know" I said, "I've only owned it for a few hours, but I'm fixin' to find out!" The look on his face was priceless...
The G26 shot flawlessly (sights were even really close), and I think I ended up about 5th place out of a dozen shooters (small turnout; indoor match, in the wintertime). Lots of fun, and fairly challenging with a new-to-you weapon.