Assuming Vermont winter for the Float, 13.6 is better than 13.2 anyway, so even if the WFCO never does 13.2 (it might) doesn't matter. As long as it does 13.6 why buy a new converter to do Float at 13.2 that is too low for the ambient temp?
If the Float voltage is too low for the ambient temp, then it will not keep up with self-discharge, which is why to be on float. But even on a proper float you need a regular overcharge to counter stratification and any sulfation. I am guessing the too- low float voltage just means you need to do the overcharges more often and maybe for longer each time.
The battery maintainer float chargers would not be any better than the WFCO at its 13.6 or 13.2 unless you can adjust the float voltage on the things. You still need the regular overcharge. (do not be confused by the little shot of higher voltage some do every so often while on float, intended to counter stratification---confirm with the hydrometer how that is going over time)