Okay, let's play stupid questions. I'll be the idiot.
When you guys say ".002 neck tension", what does that mean? .002 from what to what?
It's how much the neck gets sized such when a bullet is seated the neck will be .002 over a sized and non-seated one.
I can't say much about the other trimmers, but the Dillon 1500 just kicks ass. I have two of 'em, one on the 650 and another dedicated to .50 BMG, so I have a bit different insight regarding 'em. When you're sizing and loading a thousand, ten thousand pieces, it's not just nice to have, it's damn near required. With the Dillon, some of the trim dies are also sizing dies, so if you run an expander after, no need for a sizing die (padom brought this to my attention, but I still use the Forster sizing dies since I have 'em). For decapping and sizing stages, it just flies, as fast as you can operate it smoothly. Loading isn't as fast just because powder tends to get shaken from the brass if you're hauling ass and the cases are full. But it's still faster than any other method.
I use two toolheads too, but I have a third with only a universal decapper. I decap, clean, size, clean again, load.
They're well made, basically Foredom high speed motors with a cutting tool that has three faces so when one wears out, just rotate it 120deg. It ain't no cheap Dremel motor, that's for sure. It's heavy as hell too, kinda gotta be careful swapping it between toolheads. It's pretty easy to setup too. The trimmer is also damn near silent! The vacuum is the all the noise. I've forgotten and left it running a couple times. It's pretty light work for those motors I reckon because it never gets hot either. I don't know how you could improve on it.
I couldn't go back to doing it the old fashioned way. Not now.
The 1500 isn't exactly supposed to be used for MAKING .300BLK, it'll wear it out much faster and this is from Dillon, but it can be used for that if you want I guess. I mean it'll do it, it's just a lot of material to cut that way. They still recommend chopping it and going from there (so I just get new .300 brass instead).
The other nice thing about it is that ALL brass gets sized and trimmed the same. If it needs trimming, it gets it and if it doesn't it just passes through. The .50 is the one that gets used the most though, I haven't seen a BMG case yet that didn't need some form of trimming to bring it back to spec. And if it's tough enough to go through thousands (so far) and have zero issues with BMG, I doubt the one on the 650 is gonna suffer. Even on the worst BMG cases it doesn't slow down, it zips right through 'em. And it works as a fast as you can operate that lever, I've never had to wait on the trimmer.