Well, I think you ought to consider a "pro" body....like the Canon 1D Mark II or II-n, or a Mark III that has proven itself reliable for focusing...or one of the Nikon pro bodies like a VERY low-cost D2h or D2Hs body...once you try a real "flagship-level" Canon or Nikon, you'll appreciate why people still shoot old, piece of chit professional-class bodies like the Canon 1D Mark II and 1D Mark II-n and the D2Hs and D2h and even the D2x...because they deliver the goods, assignment after assignment. Honestly, the EOS 1D Mark IIn might be the best all-around "cheap" pro solution for you. The image quality is better than one might think...the MP count is not the real be-all,end-all...
One of the things that just does not come through in most reviews is how FAST and WELL the flagship-level bodies actually handle, frame, fire, and function...the sheer SPEED that the image is recorded after pressing the release, the sheer quickness that the mirror is right back in viewing position, feeding the AF system new data...this is the thing that so many amateurs do not appreciate about the "flagship-level" bodies...and which does not come through from reading reviews.
Like with a 5D,or a 20D, or a Nikon D70, when a field goal kicker's leg starts moving forward to kick, that is TOO LATE to press the shutter release. Seriously...with a D2 series Nikon, you can actually wait, and SEE the leg moving forward, and press the release, and be a bit EARLY on the contact of foot on ball. The difference is absolutely HUGE on slower-developing sports, like pole vaulting and high-jumping. With a 5D or D70, you get one shot of the plant of the pole, and one shot of the athlete OVER the bar and ON THE WAY DOWN,and the third frame is of the athlete on the landing pad. Seriously. In effect, you get just ONE, single chance. With a 10 fps camera, you can get one shot, and sometimes a second one, that is still quite usable. With the D2x on High-Continuous at 8.2 fps, you can shoot from head on and get four frames on the runway, two in the air on the way up, one of the athlete clearing the bar, and another just after he clears the bar, then one on the way down...it's a HUGE difference.