Here are my thoughts: I recently did the Rev in my FX-1 build. Yes, the exhaust tube on the right toe area is a problem and I thought that by cutting out the toe of that foothold and reforming it would be the right way to go.
It's not.
I wear a size 11, and I prefer to ride stand ups with shoes. By cutting out the little bit for the pipe, it doesn't allow your foot in far enough to get good lift. The correct way to do it, in hindsight, would be to dent the tube. Tough, though, because it is stainless, and you might have to remove it to dent it right, then reinstall it (hassle).
The other thing that I really really REALLY don't like about the REV's in my FX-1 (and I'll preface it by saying that it might just be the size of my feet) is that the top part of the foothold digs into the top of your foot when you try to lift. It's painful, and not just a little. Very uncomfortable.
Lastly, I found quality issues. Before I installed them, I found that they were NOT mirror images of each other, which, for that kind of $$$ they darn well should be. That was disappointing.
I have toe holds on my other FX1, and in the third FX-1 I have the 24-7 Maros-era ones, which, at size 11 shoe, are too small IMO.
I've yet to see the perfect FX-1 foothold. (and frankly, I'm not sure what the answer is)