To this day, I generally use WERD as my movement keys in FPSs and other games with similar movement mechanics (e.g. third person stuff like the later GTAs).
(Background: Came up with this arrangement by placing my hand on the keyboard
at a time when WASD wasn't the popular default it is today; heck, I probably hadn't even heard about it. Going from memory, I'd guess this happened while playing Quake II or Action Quake 2 with GameSpy to browse servers on a 56k dialup connection.)
However, I prefer the usual inverted T for typing. I won't pretend there was a lot of thinking involved in reaching WERD, but looking back it might have had to do with the "dominant" movement you do in either activity? Forwards in games, downwards when typing / reviewing some document or code.
If you're building something entirely custom, some ergo boards (e.g. TECK) use a "flattened cruciform" with the left and right keys flanking up and down in the middle, right between the inverted T and T positions you're describing. Some Microsoft Natural series boards have "narrow cruciform" with up, and and right underneath on the same line, then down.