Hi bluebug,
You're right, plyos are meant for fast-twitch, ATP-burning muscles. I was thinking of power as the maximum force produced in short bursts of energy, rather than extended endurance-type power-production that you talked about.

Regardless, plyos do help you condition muscle fibers you don't normally access when cycling. This can help to increase your pedaling effectiveness because you have more muscle fibers at-the-ready for each stroke. I especially notice increased pedaling efficiency with my hamstrings and glutes when I am effectively training with plyos, and that can be really useful for your long climbs, too. Nothing creates powerful glutes like jump squats, and lordy knows we all need powerful glutes for long climbs.

Have fun!!!