I was thinking about joining IDPA and competing but, noticed that very few people, at least here, use an H&K. Are they bad guns for competition or just not that popular?
P7s are fast but lack magazine capacity unless you can get your hand around a P7M13. Also expensive.
USPs and their plastic derivatives have tough triggers, said not to be very ameniable to gunsmithing.
There are some, so if you have a H&K, come on down. It can do the job if you can.
Once upon a time, P7M8s competed in SSP, and were thought to be the "gamer" set-up. When they moved them to ESP, they became less competitive because of capacity, so they were used less frequently.
Besides, they are expensive.