Well gentlemen, here's my ideas:
A good routine is what I have, it's simple, play with gearstick until you're sure that you're in neutral, handbrake on. I always park that way (unless on a hill) so there's not much chance of me starting in gear anyway, but it's one of those quirky modern car features I'd like to add. Might help baffle some thieves too, if used in conjunction with EFI that is, not just the starter solenoid / relay.
I agree that splicing more stuff into hydraulic lines is adding more potential problem points, but it seems to me a more correct solution than fabbing up a bracket or mounts for a switch / drilling holes in things. Ok so new cars might have electric switches but they were designed in there, not an afterthought, so retrofitting one would seem a little tacky, to me.
I'm like neat stuff like nifty switches, etc.
There would be enough pressure in the clutch line to trigger the switch right? They're meant to trigger at light braking touch so clutch actuation should have at least that much pressure.