Can anyone tell me if the later "rocker" switch type fliptop portaflex amps had the same tone as the early to mid 60's portaflexes? Should I hold out for an early to mid 60's model? I can get an early 70's model in sweet shape now for a decent price, but I've never owned either type fliptop, so I know nothing about them other than the tones I hear on the records they were used on. Thanks. John Sr.