You don't worry about repetitive strain injury from all that chording? I try to avoid that sort of thing as much as possible; even though I use emacs, I do it with evil bindings. Capslock rebound as control is useful, but the bottom row modifiers seem problematic. I can't easily reach those modifier keys while also keeping my fingers on the home row; I have to either contort my thumb or pinky in a bad way, or move my entire hand (which is usually how I use those keys.) Either way, keeping hands straight and my fingers positioned on the home row seems much safer and comfortable. I just can't imagine using a language where I have to altgr for every character I type.
Hasn't really been an issue. Occasionally, I map CapsLock to AltGr so I have a left-side APL shifting key too — it doesn't see much use, though. Also remember that it isn't "every character I type". Actual APL primitives only comprise a relatively small fraction of the total code. I just did a rough computation on four things I've been working on recently and they had 4%, 5%, 6%, and 7% non-ASCII APL glyphs, respectively.
