I think (though I might well be wrong) that the DX7 only transmits on midi channel 1, which could prove to be a major headache or a minor quirk depending on how you work.
Can't comment on key action on either, I've played on both in the past, but don't remember anything about them.
I would only go after the DX11 as a master keyboard if you actually liked it as a synth. There's plenty of choice for a cheap old synth to use as a master, so you might as well get something that you like. I occasionally use a Yamaha SY35 as a master keyboard, nice light but fairly resistive action, velocity and aftertouch sensitive and a fun little synth as well.
I like the action on old Korg synths like the M1 and 01/w which used nice keybeds (made by Yamaha actually). You might like to try something like those. The Ensoniq ESQ1 and Roland D50 were ok for synth action too, should be plenty of those around.
You'll have a lot more choice on ebay than craigslist by the way, and since it's a buyer's market for most old digital synths you'll prob get something you like on there for cheap.