JDtoys, not sure what all that you need to know, but back in 2004 when I bought my 7520 it was simply the
best tractor available for its hp range.

Most weight, (7350lbs) highest hydraulic output, (17gpm) highest lift capacity, (5500lbs @ hitch point) Most accessories that came std. Best price.
Now I know that some of the acc that I got as std equipment are now acc that they charge for, and I think that prices have gone up a little, although actually more than a little because of fewer std acc. When I bought my 7520 the only options from Mahindra were the 3rd rear hydraulic remote and the 3rd function electric valve for the loader. I ended up buying the electric valve at time of purchase and the 3rd rear remote last year.
Currently I believe that the front and rear cast iron weights that came with my tractor are an extra charge as would be the 3rd rear remote. I was told that the 3rd function valve for the loader is no longer a Mahindra option and an after market valve would have to be used at this time.
If you are going to be wanting a cab model, Mahindra is coming out with a new 80+hp model that is supposed to be out in Feb 08. Their current 70hp cab model is actually a TYM tractor with a Mahindra engine. I have not actually seen the Mahindra model, but have seen and been in the Montana version of the same TYM tractor with a John Deere engine and it is one nice machine. Might be able to get a deal on one of these the 1st of next year I would think. I would count on Mahindra's new cab model to be even better. We will see in Feb I guess.
As far as the 7520 goes, it has been a great tractor for me. I only have about 220 hours on it though, so it is not even broken in yet. The 2 problems that I have had with it are the radiator overflow tank cracked in the 14th month and I replaced it with a new updated version and a nut on the steering actuator came loose and was an oily mess. just had to track down the leak and tighten the nut. The tractor has plenty of power for me. I use it mostly for dirt work, loader, rear blade, box blade, grading two miles of road. As far as field work it gets used for flail mowing with 102" heavy duty mower, harrowing and disking with an 8' offset pull disk. My disk is really the only implement that works the tractor. It is about 2200lbs with 22" notched disks and usually the 2nd time around for me it is digging in 8"-9" deep. (axle deep) Even with that it really only works going up hill. Flat or down hill, no problem. I have found that low range 4th gear works good on the flat & downhill areas, (5.57 mph) and that low range 3rd gear is good for up hill. (3.94mph)
One last thing, I have my tractor ballasted about as heavy as I can get it. Tried first with 4 sets of cast iron rear weights, (helped very little) then fluid filled all 4 tires. That was the ticket, tractor weighs in around 12,000lbs the best that I can figure. I have R4s due to my place was burned out in 2002 and I felt that I needed a tougher tire to hold up against all the burn stuff that there was. The R1's have about 30% more traction the best that I can figure, but I have been fine so far.
If you have any questions, feel free to ask.