My gripe with .17 HMR is expensive, rimfile ammo. The range is littered with .17 HMR brass. .204 Ruger is boxer primed, reloadable.
My wife is waiting for the Ruger MkIII in .17 Mach2. It's a rimfire .17 cal in a necked down .22LR cartridge. The .22LR MkII pistols can be refitted with a .17 Mach2 barrel if desired. Release is still a few weeks away. Ammo prices and availability will figure significantly in my decision.
The flat trajectory, the additional 25 yards over .22 WMR, very little sail effect from wind, and the same effectiveness as the .22 WMR have sold me. The round is on the verge of being approved for coyote, too.
Rimfire can be fun. The prices will come down when the market expands. It's still too new for a big market. The "secret" will spread soon enough.