I used to ride (the wife now has it) a 2006 F6 that i put 1.3750" track (the sno-pro track) on the very first day. The majority of the time the sled temp is just fine, but if we get into really hard pack or low snow conditions the temp light comes on quick. On the 2006 fire cats the coolant runs through the running boards and has a small (to me) heat exchanger in the rear. I did add a set of the original scratchers and have used them probably twice each year. They are easy to install, don't cost much and don't get in the way when not in use. Personally I would put them on for those rare occasions you want/need them.
Around 9,500 miles on the original track and I am going to guess on the 3rd set of slides (I have never got to the point where I had to replace the slides but in the fall when I am cleaning the sled I notice they are worn down so I do it then).