Glenn, when you say "they will take some getting used to", are you coming from a lead player point of view? The reason I ask is that I, as a primarly rhythm player, never have had any issues switching between rounds and flats. In fact, I have used mainly flats on my 1967 Gibson ES335TDC since I got it in 1969 (although it currently has a set of rounds). I particularly like the lack of fret noise with flats, it makes for a cleaner rhythm line.
Being that this is my 450th post, it is only fitting to show a picture of my 450v63 JG:
I need to restring this one, and probably will go with the flat wound D'Aquistos as I did on my 460; I do have some T-Is, so maybe I'll try them for comparison . In any event, when I do, I'll post the results with regard to tuning and intonation.