I have experience with Bushnell Elite 1 Mile, Sig Kilo 2000, Leica 2000B, Sig Kilo 2400, and a Terrapin. Keep in mind, there can be some variance in performance between individual RF's of the same model, so when one person says his can range a 12" plate @ 1000 yds, that doesn't necessarily mean every unit of that model will do the same. For instance, a friend has a Kilo 2000. I've seen him range all kinds of stuff from 1500 - 2000 yds. I bought one and it wouldn't range anything past about 700, so there can be quite a bit of variance from unit to unit.
Here is my rundown. These numbers are from my units.
Bushnell Elite 1 Mile - I can range a 24" plate @ about 800 yds. Past that and it gets spotty. Bushes, trees, hills, building, etc can typically range from 1200 - 1500. In that range, I don't get a return every time. Sometimes have to scan around a bit to get a reading. If you were trying to range a plate or small target on the horizon at 1000 yds, I doubt that it would consistently return a reading.
Leica 2000B - Very nice glass, crystal clear picture. Readings return very quickly. Ranging ability slightly better than the Bushnell, but it wasn't enough to make me keep it. Traded it in for a Kilo 2400. The ballistics on the Leica are crap. Don't buy one thinking you can use the ballistics tables for anything other than short range stuff.
Kilo 2000 - Bought one and it was a dud. Read lots of reviews and it seems there were quite a few bad units hit the streets. I sent mine back and they promptly send a new replacement, which I sold.
Terrapin - This unit rocks. I ranged all kinds of stuff easily out to 2500 - 3000 yds. It was super accurate and reliable. It is not fast however. By fast I mean once you press the range button, it takes about a second to get your range. Then it will be another few seconds before you can range again. The Kilos are lightning fast, as was the Leica, but the Terrapin is slow by comparison. What it lacks in speed, it gives you tenfold in ranging performance. I have no doubt that you could range a plate on the horizon at 2000 yds. I would really have to get over 3000 yds before the returns got spotty. Anything under that and it would range. I sold it and regret it very much. I got wound up in the no warranty thing so bailed. I wish I would have kept it. If you are going to start shooting 1 mile plus, and want to be able to consistently range the target, this is the unit you want (or one of the other Vectronix units).
Sig 2400 - This is the one I currently use. I'm very happy with the ranging and ballistic performance. I wanted an all in one unit (range and ballistics). I had been using the Bushnell RF with a Kestrel 5700. It worked fine as long I could get a reading on the target. I realized pretty quickly that for hunting, a RF/Ballistics combo would be advantageous. Tried the Leica, but found the ranging wasn't much better than the Bushnell, and the ballistics were crap, so traded it in for the 2400. Ranging ability is very good. 1400 - 1600 is possible with the right sized plate. Bushes, trees, etc, are pretty easy out to a mile. I ranged a cow elk at just over 1300 yds. Bull elk some distance further would not range. I estimated him to be around a mile or slightly over. No dice on the big boy after multiple tries. Large stuff like houses, rocks, and hills I've gotten readings to about 1800. Sometimes consistent and sometimes spotty depending on the individual target and lighting. Ranging ability is not on the same level as a Terrapin, but it does provide quite a few bells and whistles that the Terrapin does not. It is super fast, small, and easily portable. It comes with a nice tripod mount that works very well. The wind meter is virtually useless. The ballistics (AB) have been spot on for me out to about 1600 yds with a 300 mag. At 1600, my misses were not ballistics related. They were wind calls, bad shooting, etc, but not the 2400 giving me a bad elevation reading.
So to sum this whole thing up, if it were me, and I were wanting to shoot 1 mile plus and range a steel plate that far in all conditions, I would buy something made by Vectronix. Yes, the warranty issue is something to consider, and only you can decide if it's a deal breaker or not. I don't think there is anything else on the market that can compete if you are talking pure ranging capability. I would much rather have a unit that can range well past my maximum shot distance, so that I know the capability is there and that I'm not pushing it right to the edge. I wish almost every day that I would have kept my Terrapin, and sometime in the next year or so, I'm going to buy another Vectronix unit. As much as I like the Sig 2400, and as much as it fits most of my needs, it can't compete in pure ranging performance. It's kinda like buying a 308 when you really want a 300 win mag.