The reason the ergodox thumb cluster feels so odd, is because the majority of users are not tented high enough.
On a flat keyboards, any key that would require the thumb which is further away would force the wrist to twist inwards to reach, it is this twisting which feels odd..
This is the reason why the space bar on flat keyboards are so long to begin with and reach so deeply into the palm area..
But on an ergodox, because it mimics the kinesis style thumb clusters, the distance CAN BE increased because in the tented configuration, the cluster does not require wrist twisting..
If you are using the Ergodox @ the Proper tenting angle (50-55 degrees), the thumb cluster is perfect and easy to reach....