I'm super competitive, get accused way too often of "not being in it for the fun" (usually by people who train twice a year, go to a trial, and laugh hysterically when their dog stresses and runs around the perimeter or out of the ring), and still jump my dog in Performance. Same course, just a lower jump height, lower A-frame, and usually 2 extra seconds (which we never use) on the SCT. The only thing you can't do at a Performance level is World's - which isn't on our radar anyway. Meg went to USDAA Nationals in Performance and the competition is generally just as tough as in the Championship level.
I don't think running performance/preferred/whatever your venue calls it takes anything away from the job you are doing. Meg has actually jumped up and over the side of my full-sized pickup and into the bed - of course she can jump a 22" course. But she's 17.75" tall, she has a nasty scarred up elbow that we don't know the story behind, and she is my one and only dog. I'll jump her 16" (and, more important to me, use the lower a-frame) and hopefully keep her sound and running longer.