Quick, unrelated question: Do you live close to the sea? Or are otherwise 100% sure you can/will go diving once the kid is here?
Most definitely, the best £2000 my grandad ever spent (60 years ago) was our shack at one of the
best snorkelling places around (ok, so Rapid Bay is just around the corner but that's more of a swim from the beach to the good stuff). I wish I'd met the guy to thank him, but he had angina and loved his early-morning fishing so died down there 10 years before I was even born. Anyway, Blobby is due early Jan so if we're lucky with the weather in sMarch it might get its first dunking down there (you can chuck a 2 month old in the ocean yeah?), at the very least it's going to spend most summers down there just like I did as a kid.
But yeah, might have to forego the hours-long trips we sometimes do together. At least for the first summer or two we might be limited to single-trips only while the other one stays on the sand or just splashes around in the shallows (unless we get a nana-babysitter to keep it company for a few hours).
But the good thing about the bag-housing is that we can use it to just take photos of the kid having fun in the water even without snorkelling.
So it'll probably get more use out of the water for the first year or so, that's kind of more why I'm looking for above-water specs too, like IBIS.
I know there's always the 'just wait and see what they announce next year and buy something then' option, but part of me wants to get something sooner than later for baby photos etc (I'm well planning some MF and 8x10 portraits etc, but wouldn't mind some digital ones too, more different media means less chance of losing the whole damn lot in a fire, plus I don't think I'll have that much time to develop or get scanning done, let alone set up the enlarger and mix chems).
So that was really the crux of what I was thinking, if there's no chance of anything cheaper with IBIS coming any time within a year then there's not much point waiting (R7ii might not be as affordable as a used R6 and might not make used R7s much cheaper either).
So I know that leans more towards getting a 6 over a 7, at least being able to use the 15-85 in crop mode saves having to buy new WA glass, but at that point 34MP of the R7 does start to look a slight bit better than the cropped-to-8MP R6
I've been disappointed in the effect of IBIS on EF lenses with builtin-in IS, on my EF100L it made things actually worse! I do like what IBIS does to non-stabilized lenses, even telephoto ones like the EF180L. It might not reduce shake in images, but it does make composing through the viewfinder easier.
Does that still hold true for an IS lens with the lens-IS turned off? (or is there some stupid firmware dealie where that switch turns off IS as well?) OK, so answered that myself, looks like you can't turn lens-IS off and still have IBIS on. Doesn't anyone make an EF-RF adapter with a MITM-style attack to make it look like it's got no lens-IS? Might be one of those YMMV depending on individual lenses (seeing as you mentioned two macro lenses, is it worse only close-up or at infinity too?)
At any rate, all I've got with lens IS are 15-85 and 70-300L, the rest are non-IS primes. So that might be a case of try it and see...