No, you'll want Extend on the bottom bracket, trust me. But since the actual CapsLock key is free now, you could have Backspace there – vanilla-Colemak-style! If you're anything like me you'll still end up using the Extend backspace a lot, but you'll have the choice.

The numbers have to move with the letters, or mayhem ensues. I tried not moving the right-hand numbers when I did the Wide mod and I nearly went mad. Your motor memory will and shall have a feeling for where a number is relative to the hand's home position and you don't want to mess with that.

Never using a key is all fine and good until the day you need it nevertheless. It will happen, trust me. So you don't need those keys in good positions, but the symbols shouldn't be gone either.

You don't need to know much to edit the pkl files, just make a backup and try things out. I'll help if you need it.

Since the A-Wing mod turned out to be more disruptive than I had expected, I'm writing files for the ANSI ZXCVB→XCVBZ mod, too. Phew!