Nice unit RL and a great write up...
Only problem is you should've posted this about 5 years ago when I bought 2 GRRs... or me read it.
What type of "mouse matt" did you use to get a good grip. Most mouse mats I've seen/used didn't have a "grippy" surface.
Great benefit of a shopmade one is the ability to remake those oopsies that will inevitably happen.
If your first cut is too short... Take the second cut from the longer end... LBD