I had considered a large submersible pump as an alternative to VFD's (prior to the discussion of using VFDs to alleviate our generator woes). That would certainly help reduce or eliminate cycling during the semi-dry season. But it still would not eliminate short cycling during the rains.
Our large pump (#1) pushes 8,000 gpm and our small pump (#2) is probably in the 5,000-6,000 gpm range. During the heaviest rains, the water can flow into the pond at a rate somewhat less than what pump #2 can evacuate: pump #2 will draw the pond down and eventually shut off. Under those conditions pump #2 is well-sized for a fairly long "On" period, but has essentially no reserve pumping capacity. However after pump #2 switches off, the water level in the pond rises rather quickly; then pump #1 will run, draw the water down more quickly, and the cycle repeats. A submersible or other small pump would not benefit us in these conditions.
Then there's the technical problem of tapping into the discharge pipe...