I thought I'd update this thread with the following:
1. I wasn't a fan of the EPLI, didn't like the bulk, the clip, and even though it had a "high first" UI, I didn't like clicking through the other modes if I needed to activate high, turn it off, move, and then repeat (during training).
2. I've been carrying the PN20a2 because it has the absolute best UI I've found, hands down, in that it's consistent -- leave the head tight and you'll always have "high first" no matter how many clicks at whatever rate. Unfortunately though, this has not proved to be a durable light as I've gone through 3 of them, and it usually is a result of operating in a salt water (tropical) environment and the switch seizing up.
3. I recently bought a second generation Preon 2 since they added the ability to change UIs, but although I really truly wanted to like this light, FourSevens is still unable to design a tailcap button that doesn't stick 30% of the time, and in my case the button has already failed in the two months I've owned it as it now only functions as momentary on.
So back to the PN20a2, and at this point I've decided to basically clone it in Titanium with a higher spec switch -- I'll post info when I get around to making it.
