I built an ergodox and used it for several months before selling it on eBay. The thumb cluster positioning is worthless. You only can easily use the double-sized keys, so I ended up making the other ones pageup/pagedown/home/end left/right/down/up since they don't get used as often. The bottom most row keys are awkward to use too, making the whole ctrl/alt/win key positioning not as fantastic to find a setup for.
I had a Truly Ergonomic (TECK) as well, and really liked it for the size and layout minus the ctrl/shift keys being swapped. I could not get adjusted to that after two months of using it. I ended up returning it because there were terrible key ghosting issues, but it looks like the open-source firmware for it has helped address this.