This reply applies to a 520EXC, I am not sure if the MXC 4 strokes have the same valving or not. I came off of a YZ 250 that had the works done to it by MX Tech, and was ridden in all types of terrain and different types of racing. I am 6'4" and 220. On the front, the 4 stroke EXC's are set up very soft stock. They are not harsh on small hits as some have said about other KTM's. The low speed circuit works very well for me. However, on big hits, problems arise quickly. Mine bottomed way to easily. After the first ride, went to .46's and Mx-Tech's suspension oil (mostly made up of Mobil 1 ATF) set at 120mm. This helped a bunch, but I have made my mind up to have them re-valved for more high speed compression.
On the back, I went with a straight rate 9.0, but could probably use a 9.4. I could not get the proper sag with the stock PDS 2 and Mr. Wilkey at MX-Tech is a proponent of straight rate springs for the PDS rears. After taking his advise, I am too. My bike does not exhibit any of the front end push others talk about. It corners at least as well as my 2 stroke Yamaha. I am happy with the PDS.
With work, the suspension will be fine. At your height/weight/speed, it will defintely need spring changes and probably valving changes before you are happy. Properly set up, it is hard to beat this bike.