First, what I shoot: assorted range of things, but mostly portraits (not in the studio thus far), candids, low-light (especially now since it gets dark at 4pm). I want something that shoots well in low-light, and by that I mean an bang on AF and has the ability to shoot clean shots up to around 6400. I don't do videos.
Second, my gear. I've got a 60D and a 5D2, which work well enough when it's bright out, like any decent body should. Low-light (this is a revolving theme here), is the issue. The 60D is meh, to put it bluntly in terms of high-ISO quality and AF when shooting indoors/at night, and the 5D2 is absolutely terrible when it comes to AF in that regard (though I'd be hard pressed to get usable images at ISO 12800 from another camera after running it through post). My other lenses should be in my sig (including an unlisted 85 1.8)
So my question is three-fold. One, will either of the 1-series bodies solve my issues? I'd like to take full advantage of my 24 which is why I'm leaning towards the 1ds line, but having never handled one, is the ISO ceiling of 1600-3200 a dealbreaker for most users out there? Yes I realize there is something called a flash, but sometimes I can't use one so I maintain my concern.
The second question: are there are any options I haven't looked into? I'm open to new techniques, and it's possible (and quite likely) that I've forgotten to mention something here, so I'm all ears.
Third, and I fear that this is the answer to my long-winded post, is a switch to Nikon inevitable? Hold the stones and rotten fruit. The D700 has great AF, is full-frame, and trounces the 60D in low-light and arguably gives the 5D2 a run for its money.
I'd like to stay with Canon since I've already got the gear. I have brand loyalty, but only to a point, and unless there's something I'm missing/forgetting, Canon's gear doesn't suit my style and needs as much as Nikon does.