There's a bit of similar discussion about Roto flats here
I've sort of gone off them due to their inconsistency.
It's a shame, because I really liked the sound of the E and A strings in both the sets of SM77s I tried.
...... Back I went to Chromes!
'80 Rick 4001. '84 Fender Power J Special, '05 USA Jazz, '11 USA Precision, M Miller Jazz. Peavey T-40, Zoom B3. GB ShuttleMax 12.0, GB Uber410, fEARful 212.