|The advantage of a combo unit is that you have one less power brick to worry about and one less cable to connect modem and router plus the combo unit is likely to be cheaper than a seperate MODEM and Router.|
I have used the Zoom X6 and it is a very good modem. Zoom also owns Hayes Modems. Hayes virually invented the Modem back in the days of dial-up so there is a lot of experiance there, Dial-up modems still use the Hayes Command Set. It is a de-facto standard originating back in 1977.