upgrading from a canon 400D

It's about time to upgrade my body, and i'm in a bit of dilemma. But, first things first.

The main reason for the upgrade is the awful performance of my camera in "high" iso -and by high iso, i mean 1600.

Most of the time, I shoot basketball matches. Other than that, I try landscape photography when on vacation.

My lenses now are a canon 70-200 f/4, a CZ 50mm 2.8 m42, and a Σ 17-70 for crop bodies.

My main choice is the full frame 6D, but the AF system concerns me. Should I go for a FF camera, with excellent high ISO capabilities, but with crippled AF system, or a crop body (60D? 650D?) and 9 cross type AF points?

The fact that i don't have ff capable lenses isn't an issue, for now. as a matter of fact, since i got the 70-200, i rarely use the Σ.

PS I should mention -even if it is quite obvious- that i shoot basketball just for my pleasure - as a hobby.

My 60D works just fine in sports-shots. I use center-point only and fast glass: 85 1.8 and Sigma 70-200 2.8 OS. Learning LightRoom, along with proper high-ISO shooting technique can improve your ISO 1600+ shots, A LOT.

Might as well look into the 7d over the 60d - the AF is much better. IMHO f/4 is no fast enough for indoor sports, so you might consider something like the 85/1.8 or 135/2.

I've never shot a 6d, but AF would probably be good enough with an f/2.8 or faster lens using center point - the 5d mark 2 was.