BTW, is it completely fair to compare the HDS 170T to the E2DL 200lumen? The HDS isn't really 170 lumen - at least not for very long. The HDS is 170 lumens for 10 seconds, and then it drops down to 120 lumens. Now to me, this is a perfectly acceptable tradeoff, particularly for a single CR123a light like this. However, I feel it would be irresponsible not to point it out to the OP.
I don't want to seem like I'm bashing the HDS - I'm not. I think what they are doing is smart, works extremely well, and in actual usage is a total non-issue, except it makes the battery life for this light better.
The SF, though, will deliver 200 lumens, for real, for close to 2 hours as I recall. If the lighting conditions under which you'll use this require that much light, you'd be better off with a SF. Examples: Searching a mostly dark apartment after walking in off the street during daylight. You're going to want all the light you can get I'd think, as this is about the worst possible case for your vision. On the other hand, if you are doing this stuff mostly at night, the HDS way is probably totally fine, and the light is much more versatile. (120 lumens is still lotsa light under most conditions.)
Anyway, I'm not sure if the HDS 170T is a replacement for an LX2 or an E2DL, at least not for a law enforcement officer. If you really seriously need full output from the light for an extended period, the HDS is not the right choice. (Most of us, however, really *don't* need full output for an extended period.)
I will say that in my opinion, it absolutely, and unequivocally beats the ever living hell out of the E1B though. (HDS is markedly superior in just about every way I can think of - brighter, has more modes, lower lows, and you won't drop it all the time like an E1B.) And for us civilians, yeah, for the most part it's going to be a better option than either the E2DL or the LX2.
I don't think it would be unreasonable for a person to buy both of them. I realize, though that it's a lot of money to do that.