Thanks, Chaitanya.
Interestingly, he joins the chorus asking for IBIS. Unless there is a significant downside, why not? Wouldn't the 50mm focal-length be a good candidate? I like the bokeh...
I wish he didn't use LR screenshots for his samples. And I wonder how the bokeh looks with trees in the background when stopped down a little bit. Nervous like the EF version of the 1.2L? Or is that better controlled?
Still, nothing here to make me want the lens less!
IBIS does make it more difficult to dissipate heat (one reason why Sony cameras had overheating issues with 4K), and in some implementations, the sensor can not be locked in place. This can be bad for time lapses or for wildlife shooters.
For most applications, I don't find IS useful at the shorter focal lengths because it tends to be less effective (in stops) and the shutter speeds get so long that it's not practical for live subjects. However, if Canon chooses to put IS in lenses, I'd rather Canon put it in the 2.8 zooms rather than the fast "L" primes for the shorter focal lengths. Lenses designed for general purpose use will encounter situations where IS is useful more often than fast prime shooters. And because IBIS is less effective than lens IS, I'd expect the benefit to be even less for a lot of added complexity. Ideally, it could be coupled with lens IS to get something slightly better than just lens IS, but again that has to be traded with complexity, heat dissipation, etc. Also think of run-and-gun video shooters -- a stabilized lens trio of 16-35/24-70/70-200 would be used for most scenarios, and at point I'd rather have IS lenses than no lens stabilization and only IBIS.
I find the IS for the 70-200 and above to be useful. 85 f/1.4L is not often useful because usually I'd rather carry a IS zoom for general purpose/travel and if I'm in a portrait situation, I'm relying on my flashes for the main lighting. I do like the 16-35 f/4 IS for building interiors but again, it's about 1-2 stop benefit and I don't do that often, so much so that I should consider selling the 16-35 f/4 IS now that I have the 16-35 III.
I found out the hard way that IS is useless for taking pictures of waterfalls from foot bridges. The vibration induced by other people walking on it was too much for IS to handle. Even with IS
Going off on a tangent, I'd love to see what a RF version of a 85mm "L" prime would be like. The engineers talked about the IS and the rear element limiting the 85 f/1.4L IS design. The RF would allow the last large element to be closer to the sensor plane and give more space for placing the IS unit. I'd love to see a return to f/1.2 for the 85mm focal length...