The heavy duty branded Velcro like this is more than you'll ever need (you can buy it at Homebase, UK peeps):
The glue on that will last forever and the hook/loop is strong enough to hold a raging bull.
But the stuff that comes with the Pedaltrain is fine, I prefer it because it does the job and it's easier to pull apart than the heavy duty stuff. However, the adhesive is starting to come away VERY slightly from the board runners at the edges.
Also, I don't recommend covering the entire pedal in velcro, especially when using the industrial stuff. Makes it much harder to pry off! Little strips are the way forward...