I bought the x-keys pro, and it's collecting dust. As an ESDF user I found my hand to be REALLY uncomfortable on the xkeys pro since it only has 4 columns in the center of the pad. I couldn't use it as a keyboard replacement, and I hate moving my hand off my movement keys. If it had 5 columns in the center i'm sure i'd use it. One thing I've considered but havent' taken the time to do, is rotate the xkeys pro 90degrees so I do have more columns. If I try it i'll post about how it worked out.

Btw- to clarify, the issue i'm having with the 4 columns is that movement keys take 3 columns (SDF) and then my pinky rests on an action button and my index finger is ready to move one space to the right to hit an action button, therefore needing 5 columns. The xkeys pro is setup to have 2 columns, a space, 4 columns, a space, and 2 more columns. The gaps between the center button set and the flanking sets are too large to for my pinky and index finger to comfortably reach without lifting my hand.

I think WASD users will find the xkeys pro to be right at home though. Because your pinky doesn't rest on an action button, but a modifier (shift), so the x-keys pro could potentially be a keyboard replacement for those users.

The x-keys footpedal that I purchased gets used all the time. I highly recommend one of those.