I am considering purchasing the Digitech EX-7 Expression Factory pedal due to that it has multiple effects in one wah sized pedal. I've read plenty of reviews and for the most part it sounds like a great deal.

However, it sounds like most of the reviewers were using the built in distortion models with the effects, where as I would be using my amp's distortion. I am wanting to know if the effects would still sound good using amp distortion or if the distortion models built into the pedal are needed for a good sound.
Sounds good with either, it's just easier to get a good sound with the onboard distortion/OD effects because they've been pre-tuned to suit the effects. But in theory it is possible for you to get a better-suiting distortion sound with your own distortion/OD, so yea.