For those that play both Eb and F...

[Conn 2J CC]

For me it depends. Back when both my Eb and F tubas were 4 piston 1 rotor horns I had a very hard time. Now my Eb is a 3+1 and my F is 4 in the right hand and 5th in the left and I have no problems going back and forth. I play all four normal keys and they all have different valves set ups (BBb 3 piston, CC 5 all in right hand, Eb 3+1, and F 4+1). Now that they all have different valve set ups each key is like its own setting in my mind. It works for me.

That's what I could have used my freshman year in college - two Tubas with different valve setups. The Band Director (a Saxophonist) insisted I continue to play Bb Tuba in Band while learning CC Tuba for everything else. According to him, having a CC Tuba on the bottom of a Bb band would "wreck" the group's intonation. Since both of the school horns I used were four rotor horns of comparable size, what his erroneous "notion" wrecked was my nerves - I regularly got confused about fingerings and had to stop to think which horn I had in my hands at the time. After a quarter (it was a quarters college) of that hassle, I finally disobeyed him and started playing the CC Tuba in Band. It took almost a month before he caught on. Since he'd never complained about my intonation during that month, so much for his notion....