The quality difference between md and dat is most certainly audible, although for 250 you can get a jukebox, which is what I would do at this point. The only real advantage to MD would be for stealthing purposes, which IMHO isn't worthj a damn since a m1 or something is not a whole lot bigger and far and away better! The akg standard t bar can be had for something like 18 bucks new. Level adjustments, for me anyway, are always on the fly, although one can judge approximate levels through the pa before the show starts. I shoot to begin at around -6 db peaks, and the start pushing them from there. I usually tro to peak at -1, but don't mind the occasional over. To be honest, I have found it damn hard to cliup the mini-me, even when the P1 has stated 0db peaks.
Hope this helps
Daryan