Ok. lets talk lenses for a moment.
What did you have for your t3i? Full frame EF or cropped sensor EF-s...?
Obviously this will mean a choice do you keep your lenses or do you upgrade them as well.
For sports you want fast AF, and you want a fast bright aperture as this a) REALLY helps your cameras AF, no matter what camera you buy, and B) generally gives you sharper pictures per aperture....
If you currently have anything with a variable max aperture such as f3.5-5.6 then for sports you want rid...
You want f2.8 USM L zooms, or f2.0, f1.8, f1.4 USM primes. These are the fast lenses which will get the most out of your camera... Slow aperture lenses coupled to the best body are still going to be slow aperture lenses.
So this requires some thought.
Heres my take on a body..
The T3i AF is a bit basic for sport. I have a T3i and just don't use it this way. I did with my XTi. If you select centre AF spot only, and use only AiServo AF mode, with a fast USM lens (I had the 200mm f2.8L II at the time) then with the right technique (focus point subject tracking for a few seconds prior to first shot, multiple frame rate, stick to JPEG where you can) THEN you can get ok sports shots from a Rebel. In fact you can get pretty decent individual sports shots from a rebel. This worked for me for speedway motorcycling, jetski's, soccer.
By individual I mean from a burst of 10 you may get 3 keepers.
The other point to make is that being APS-C the XTi and my current cameras wrangle that extra reach out a lens as well.. My 200 became a 320 f2.8 equivalent, my current 100mm f2 becomes a 160mm f2.0 equivalent, and my 70-200 becomes a 115-320 f2.8 equivalent.
Fast lenses with great reach for sports. And not totally out there money (the 100 f2.0 is quite modestly priced...)
The 7D ticks the weatherproof box, it has more than double the frame rate, a forthcoming firmware upgrade is going to expand further its burst depth, and add the all important manual controls to the audio.
The 7D has two image processors but also a third dedicated AF processor. This was a first outside the 1 series at the time of launch. This lets you tweak AiServo response and bahviour, which for sports is essential. You will waste a few shots setting the camera up, but once youhave, it becomes very much your camera. Your keeper rate will jump up massively with the right technique.
And it makes it by far the better sports camera over the 5D2.
You will need new batteries, and new memory cards BUT perhaps not new lenses (although you may need these in any case)
If you were happy with the 5D2 AF (not a dedicated sports camera, but again with the right lenses, & more cross points ) then you would as likely be happy with the AF and burst depth on the T4i...
But with the benefits of the lens cropping, the benefit that your batteries and cards from the T3i will fit...
If you want weatherproof buy a Kata raincoat.
I also think the cropped sensor bodies are better in some regards for video than the 5D2... They exhibit less rolling shutter and critical focus is easier.
So the money is on the 7D... your dream camera sounds like the 5D3... Canon aren't going to substantially undercut that with anything remotely similar.
But almost important, if not more important, is the right glass.
I'd rather shoot sports with fast lenses on a rebel or x0D, than with a 7D or 5D3 or 1D with slow consumer kit lenses.
And if you buy fast EF primes or fast EF L zooms they will be working for you in 10 years time. 15 years time.
You'll be onto a new body after 3 or 4 years typically...
