I have a Roland EV-5 and I would advise you to never ever purchase this pedal.  I got it on e-bay for about $30, which is 40 cheaper than you can buy it in the stores, and is still far too much money for this piece of junk.  First of all, it's plastic and I know it's going to break very soon (I've had it for about 2 weeks).  It also doesn't sweep right.  It finishes the sweep when it's about 75% of the way back towards the heel position, so you'll start sweeping from heel to tow and it'll do nothing, then just jump on you and catch you off guard.  It also seems to be wired backwards for working with the M13.  I mean it still works, but you have to re-set all the defaults to go the other way.  Like with Volume for example, the factory defaults on the M13, when used with the EV-5, have the heel position as being full volume and the toe being no volume.

I have seen other people talk about Mission Engineering pedals.  I plan on buying one very soon.  I put a link at the bottom of this post, and about 5 pedals down on that page, they actually have one specifically designed for Line 6 products and have a video demoing the thing with an M13.  On top of that, it's in the same casing as a Dunlop Cry Baby so you know it's rock solid.  I can't say for sure that it's great because I haven't actually tried one myself, but I have heard lots of positive reviews and after using the Roland EV-5, I can tell you that there's very little shot that it could possibly be worse than that pedal.

http://www.mission-engineering.com/Mission-Engineering/Products.html

I may offer a lone voice of support for the EX-1 here.  I've had two of them on my pedalboard for nearly ten years now, and I've not had any issues with them.  Actually, they've outlived many other pedals, lol!  I know they aren't what I'd describe as "heavy duty" by any means, but they do what I need them to do.  I guess if I were actually using the wah on the M13 or really rocking the pedal back and forth a lot, I'd probably get one of the Mission Engineering pedals.  For now I'm happy with EX-1.

I actually do have one Mission Engineering product.  I have there little XPB on this page that I use with my M9.  I have it mounted right on the edge of my board, and I'm able to turn it with my foot.  It's works well for what I use it for.