Separate ones I would say too , I also had one of those combi things and the drier on it was awful,
it took loads of electricity and ages to dry ,
here is a tip you may find useful
if you can spin your towels twice after washing on a fast spin
and maybe place them around the shop of an evening after they have been washed ,
you could dry them in the morning it will be cheaper electicity wise as they will be nearly dry ,
also have you got anywhere to pop them outside for the summer ?