No expert on the layout, but could work. I'm just not sure how you are going to use all those extra keys (in terms of getting to work with your operating system :p).
Regarding the PCB, you don't NEED a PCB, since it's a fairly regular grid, it's quite easy to hook them up using loose wires. You will still need a backplate to put the switches in though.
If you have a plate, you don't need a PCB. You can use a Teensy 2.0 as a controller and wire up the columns and rows by hand with diodes no problem. The key functions can all be done in the firmware on the Teensy, no wiring changes are needed once you have the basic grid wired up.
That layout is not stupid at all, but finding keycaps for it would be difficult unless you would settle for blanks or all keys the same profile.
matt3o has made a keyboard (http://deskthority.net/workshop-f7/custom-65-finally-finished-t5663.html) that has almost that same layout, except for the bottom row which has a regular-sized Space bar. We were discussing on Deskthority about making a run of PCBs for that layout that would fit inside a Poker case (of which there are many third-party cases), but discovered that the switch positions would overlap (http://deskthority.net/workshop-f7/group-build-prototyping-phase-t7474-720.html#p161666) with the cases' standoffs, so that idea was scrapped.
Many people do actually hit a 2u Backspace in the middle, and that 1u Backspace is in the middle of that.
However, I would like to suggest that you put a large key on the bottom row also for the left thumb, and map that to Backspace. Then you could map the key above \ to Delete and use a column of all four keys from the nav cluster (PgUp, Home, End, PgDn) on the right side.
Also, if you want to sell a few, some prospective buyers would rather want to hit Space with their left thumb.
http://www.keyboard-layout-editor.com/#/layouts/699b49bcd0f360942affa3881ba06cdcOverall looks nice, but I’d recommend slightly changing your bottom row. If you put a 2–3 unit wide key for each thumb, with their inner edges roughly aligned with the edge between G/H, I think it’ll be easier. (I recommend using one for space and the other for either shift or backwards delete.) Then you can put some smaller keys next to those on each side, in whatever layout.
http://www.keyboard-layout-editor.com/#/layouts/699b49bcd0f360942affa3881ba06cdcOverall looks nice, but I’d recommend slightly changing your bottom row. If you put a 2–3 unit wide key for each thumb, with their inner edges roughly aligned with the edge between G/H, I think it’ll be easier. (I recommend using one for space and the other for either shift or backwards delete.) Then you can put some smaller keys next to those on each side, in whatever layout.
Here’s my version from a week or two ago:Show Image(http://i.imgur.com/r1d2DF0.png)
What JP keyboard is that?