I have this pump and I like it - it's been in service for several years now and is reliable. It has variable speed though I usually run it at the maximum ~3 gal/minute. They changed the design of the prefilter a few years ago since the old one was tough to unscrew and clean; I just bought the updated filter unit so hopefully it will still work. The only limitation (for my wine operation at least) is that it isn't built for pumping large volumes of thick liquids and when I move large volumes (eg drawing off free run from a 1/4 to 1/2 ton ferment) the filter can get clogged and need cleaning.
Diaphragm pumps are gentle on the wine but flexible impeller pumps are too (eg where the impeller vanes are rubber). In time I might upgrade to an impeller pump for more efficient processing of larger batches, but I'm sure I'll keep using this one for smaller volumes (eg carboys).
