Whoa! Am I doing this calculation right: $90,000 yen = $1,153?
Sigma typically lists outrageously inflated MSRP, but I didn't think Tokina did. Or maybe things are just more expensive in Japan?
Anyway, it says the new lens won't be out in a Canon mount until July. Can you wait that long?
Test reports have identified chromatic aberration as an issue with the 11-16 so it would be nice if they could reduce that. Although I have to say I've never noticed an unusual amount in real life. I am very, very fond of my 11-16 and have never found its supposed flaws to be a problem. Some people complain about distortion, but it seems to me that if your shooting an ultrawide, you ought to expect some distortion and, in fact, that's half the fun.
I'd probably see what the real street price is going to be and decide then, but it doesn't sound to me like the improvements are that significant.