5E5 vs. 5E3 - design & sound differences?

[RomanS]

Taking the obvious (different speaker sizes, different output tube types) aside, what are the major design differences between a 5E3 and a 5E5 (not 5E5-A)?
What effect would that have on sound?

If I was going to build a 5E5, and used 6V6 tubes in it instead of 6L6s, would it sound like a 5E3, or different, maybe with more clean headroom (I now, a tweed Pro isn't exactly a clean amp, either...)

Has anybody tried using 6V6 tubes in their 5E5?

[PremiumPlus]

Except for a lower 1st stage cathode resistor, an extra 16uF of filter, different rectifier and output tubes, a 5E3 is essentially a 5E5. They should sound quite alike, with the ProAmp sounding a little dirtier due to the added gain in the first stage. In fact, I'm going to try mine with a 5U4 and a pair of 6L6s this weekend. Should be fun.