I went through the exact same thing, but I went the other way. I had a Rockstar, wanted to upgrade and wanted easier positioning for lower/flatter toms. My original plan was to get a kit w/ 20" bass, but NO ONE stocks those, so you have to order them... And I was impatient, so I got a superstar/hyperdrive (they ARE stocked and its the same 2" height diff, the 2" is just removed from the toms instead of bass).
I like my kit a lot, but lately I'm starting to think the whole low/flat thing isn't all its cracked up to be, for me anyway... When I got the kit in the summer I positioned everything as low and flat as it would go (and it was a noticable difference from the Rockstars). Then a few weeks ago, at my lessons on my teachers kit, I noticed that I was having an easier time hitting the rack toms with them slightly higher and angled (like they were before); the toms were closer, it was less of a stretch. So I went home and changed accordingly.