I just wanted to say, I got my hands on a Matrix Abel earlier in the month.
The board was great, amazing anodization (though I had the MAO Ceramic White). It was odd to use such a low angle, and a rather light board but otherwise no complaints about the build quality.
Of course the non-programability of the PCB was a huuuuuge pain. I looked into as many ways as improving the board, though I ended up trading the board off. Here's what I found as good ways to fix up the board:
1. The PCBs you want are A.87 PCBs. Replacing your PCB with an A.87 PCB will give you all the programability you could ask for really, though there aren't any plates that I found that will fit with the case. I've checked Kin's TX87 PCB/Plate, but those are actually too big for the case. The Mech-27 plate doesn't fit the screws in the case, but the PCB should work. So, you could replace the PCB rather easily, but you'd need to get a plate custom made if you want to add compatibility for like split backspace or split right shift for example.
2.
https://geekhack.org/index.php?topic=72052.0 Hasu's USB-USB converter should give you full programability as well, from what I assume. Probably the least work you'd need to do to at least give yourself full programability, but of course the plate will still leave you unable to adjust your keys to match what you do.
