Have the old MK-2 unit. Worthwhile to upgrade? All comments welcomed.
It depends on many factors:
Which pads are you using?
how many outputs do you need?
did you mod your module?
if you're using the 2box pads then there is no need to upgrade
if you need 6 or 8 direct outputs you don't need to upgrade
if you moded your module there is no need to upgrade
do you play the internal sounds or import samples from SD3 and the like?
do you use the headphones out or use a mixer? There is the issue with the drumit 5 headphones out "coloring" the sound, which resulted in kits from VST“s sounding different, usually pretty bad, than when played directly on the computer, I was the first to point that with the drumit 3 they fixed this and now the phones out sounds much better and almost identical to the kits on the computer. I would assume the next drum it 5 will have the same phones out as the 3 so that could be a reason to upgrade.
The rest is the same as the drum it 3, support for pads and cymbals from other manufacturers, same software but no slow usb 1 port...