XSi to 60D Upgrade... very specific questions/ issues

I have decided that if I upgrade now from my XSi, it will be the 60D. All other cameras have been eliminated. It's either the 60D or keep using my XSi and maybe save for a full frame or whatever else comes down the line.

Having read through some of the threads here, I subscribe to the advice that I should NOT upgrade unless I can actually identify a limitation on my current body that can be remedied by upgrading. So I'd like some advice on this issue.

Obviously I'd get video ability, but while that would be nice, I think ultimately it's not a must-have for me, as I do have a camcorder.

The three biggest issues for me are:

(1) Low Light capability: I am ok with my XSi up to ISO 800, not too pleased with 1600, and obviously no ability to go higher.

(2) AF : AF seems a bit slow, esp tracking moving objects.

(3) IQ: I'd like a noticeable (even if small) improvement in overall IQ when comparing with identical lenses.

I know there are tons of other "considerations" such as handling/ build quality/ size, but I don't care much about this right now, as I find my XSi adequate in those areas. The above 3 are my primary and probably only considerations in upgrading.

So my question would be: Would a 60D address and improve upon these issues (thus making it a legit upgrade), or are these things that can and should be remedied through better photographic technique and practice (thus something my XSi can handle)?

Thanks!