Well, I did something I always said I'd never do - set out on a five week trip with an untested lens.
I took my a99 with 70-400 G and the a7r with the EA4 adapter and 24-70 ZA, reasoning that if either camera malfunctioned I'd still be OK.
But on my way to the airport I dropped by the Sony Store where they just happened to have one (only one!) 24-70 FE OSS. Needless to say, I bought it. And I used it. Never tested it in a formal sense - just used it for five weeks and over 2,000 exposures. (The ZA never got mounted let alone used.)
The lens, as Tim has said, has epic distortion. I've never owned one this bad, but for my photography it is really not an issue. For the few shots I took of buildings or ones with straight lines, I switched to JPG (and RAW) and let the camera correct, which it does quite well.
In all other respects the lens in day to day use is an absolute winner. The OSS works very well - I have some maximum ISO shots in twilight at 1/15th sec. and they're noisy but very sharp. Landscape shots in normal light are crisp and contrasty with great micro-detail. I'm itching to make some 30 inch prints!
I find, now I'm at home and have downloaded the files, that f5.6 seems to be the best overall aperture for my shooting, though f8 is equally effective.
I'll post some shots in the next few days.