Got a 2" lug 136" challenger on my 2006 crossfire 7, 2.52" pitch on stock drivers (as far as I know they're stock, the track was on when I bought it). It looks like there's still room for more lug height as long as I don't run the track looser than spec (the track becomes rounder as you go at high speed so the track bends out, more so with a looser track).
After all, the 141" M7 came with 3 pitch track with 2.25" or was it 2.3" lugs, and it has an identical tunnel all the way to the back piece where the end is different.
My future upgrade (when this track is toast) is to go with off-set rear axle and 9" wheels, with the M7 drive sprockets and the 9329M (141") track. Which has 2.5" lugs that I'll cut down to 2.25 if they hit the tunnel at full speed and proper track tension. It has 3.0 pitch so the track is softer to squeeze around the wheels than the rather stiff 2.52 pitch track. With the 2.25" lug height I have the exact same amount of lug in the snow as now (skid length divided by pitch, multiplied by lug height, multiplied by average lug width on each row, equals square inches of lug in the snow).
I will however gear it down when its time to change gears for maintenance reasons, that and heavier clutch weights will reduce belt slip.

 

I don't have a 600, but the best thing I did with my 700 was add rail extensions and drop in a 144x1.75 Backcountry. Nothing else was "needed" except the rail extensions, but since my DD needed a rebuild anyways, I geared it 55/65. Then add the taller mountain seat and bar riser, and you have the sled as it should have been from the factory.

 

Really? 55/65? The M7 is geared 57/63 with the exact same clutching as the stock crossfire 7. How's your top speed and what rpm do you pull?

 

I am running the camso Backcountry X 1.75" lug track and love the thing! Plenty of clearance on my 09 xfire 600. Its a 141x2.52x15 track and it changed the handling of the sled. I probably could get away with a 2" but for trail ridding by me thats a little to tall.