I ended up buying the EH 12AX7's. Will report back once they arrive and get a little run-time.
Honestly, I don't have experience with higher-dollar tube amps so I don't know what I'm missing. Coming from solid-state, the Reisong is much more laid back and listenable at all volumes on the La Scala II's. In general, I prefer it over solid-state. The only thing I miss is the top-end sparkle of solid state. Maybe a higher quality tube amp wouldn't sacrifice that as much. Someday, I'll find out for myself. But for now, the $500 A12 is awesome for the money - just wish it came with a remote.