See what I wrote about my MIJ Strat that I Kahlerized, shown in this thread. I bought a used takeoff from a "vintage" Jackson. Yes, I had to lie in wait for it...but when it came along, I was ready, and I think it was only about $135. I put the time into completely disassembling, cleaning, and lubing it (which is a pretty straightforward process). They are an excellent, and eminently serviceable, product. The original low E string hook was broken, but I replace my low E string hooks with ones that accept a larger string anyhow, so no problem. Brand new part, retailed from Whammi World, dropped right in. Put a high tension spring in it, to counter the 11s I use. Also a brand new part from Whammi World.
Kahlers are easily adjustable for string spacing, height, and intonation. They are easy to service and repair. Cosmetically, they are perfect on a Strat; the baseplate fits right into the stock vibrato notch on a Strat guard. You need some neck angle for them to work their best.
You need not use them with a locking nut, and you need not do vibrato acrobatics with them (but you certainly can). They make an excellent general purpose vibrato.
They work best with Fender bullet end strings, IME.
Except for the straight back edge on the vintage baseplates (vs. curved today), there really isn't much difference between the old ones and the new ones.
Even the imports are good (4300 X-Trem).