While yes the matrix layout is _way_ better, the downside is that if you ever type on a standard keyboard you are immediately frustrated. I imagine it would depend on your working environment, but for me the combination of using a laptop, working with co-workers, and then using my desk with my awesome ergodox means that I am often fighting my own muscle memory to continue typing at a high rate of speed.
There is something to be said to conforming to what most people have. Splitting the keyboard gives me a good compromise, I can still have my hands in relaxed positions, and while I am not going to be as fast as when I am on just the ergodox ,I gain by being much faster working in the other environments I often find myself in.
That said, this is why I am not using colemak on my ergodox- I dont want to further distance the two keyboards.