Tradcat,
The way I see it, is that split or 3 under is an option closely related your your aiming method more so than a form "thing." It shouldn't really be a problem relating to how much cant you decide to use for a given shot.
You don't mention what it is that is troubling you, but 3 under does require that the arrow snaps on the string and many using this system use two nocking points -- one above and one below. If the arrow stays on the string, 3 under should not in any way impede a positive cant. It could get problematic with a reverse cant.
I personally don't feel the same amount of control 3 under, so I don't shoot that way much. As far as the noisier bow is concerned that seems to be a common report and one that I find too. Gringol suggests a technique to try, you may just have to "play around" with it to find out what works. Some bows can be quieted and some cannot.
This is a personal opinion only, but I don't see that 3 under or split is anything other than accommodating an aiming preference. Neither one is inherently more accurate than the other. Again, my preference is split but only because I feel more in control than with 3 under.
Arne