[MadMax]

I regularly play dual pistols, but not with NY reloading in mind. However, there are some issues common to both shooting styles:

-common mags are very handy between multiple guns
-common guns make for less acclimitization between guns (i.e. getting used to sight picture, grip etc)
-when holstered, guns are heavy compared to mags

There are other concerns like speed of holstering which can be pretty annoying. With dual pistols, I don't find myself putting a gun away in a hurry so it's okay that my holsters aren't rigid kydex type holsters. I would guess that NY reloading with several pistols would require holsters which stay open for rapid holstering. You may be hard pressed (and broke) procuring high end holsters for multiple pistols. Cheap out on holsters and you'll find yourself fumbling drawing and putting away your guns. Lots of guns in cheap holsters also means a higher chance of losing a gun and more heavy boingy bits which may shift around when sprinting.

If you plink away at targets at extreme range, you usually have plenty of time to swap mags. If you can't settle a close engagement with your first mag and can't prioritize ducking for cover to swap mags, you're probably going to be shot pretty soon standing in the open bringing the next gun to bear. Shooting from cover almost always provides an ample opportunity to swap a mag.