Personally, I find the 85mm 1.2L II one of the most difficult lenses to hold without shake. It's the shape which makes my hold awkward and balance different than all other lenses.
I hope the shape of the 85 1.4 is a little longer, maybe not so "fat." Certainly IS will be a huge help, but even more so if the ergonomics are better.
Did I miss the memo showing what the new lens actually looks like?