My boat came with the stock breakdown frame from Aire. It is 72" across with 28" between the tubes. I run 10' oars with this. This size has worked well for me so far. The closeness of the tubes helps me a lot when bracing and when trying to climb back in.
Of course, I have never even seen another Cougar around here, so I never really gave that setup much thought. It would be interesting to try the 2 different frame sizes side by side to see if the extra foot and half in width would really make that much difference either way.