tam17, I use RCR123s, so the cost of CR123 primaries is not a concern for me. Yes, RCRs cost $4-6 apiece, but they've lasted for years, so...:shrug:
The difference in length is one of the factors I've been wondering about. The EC1 looks like it might actually be too short to hold comfortably, even though the mode of operation lends itself to being pinched between thumb and forefinger. (then again, my backup EDC is an Aeon, so maybe I don't really care about length?) I can't say without trying whether it actually is too short or not, though.
Also, the EC1 has shorter threading on the tailcap, and that has me wondering whether the tailcap tries to pop off as soon as it's loosened a bit for lockout. Another thing I can't say without trying.
Has anyone noticed problems in either of these areas?