Considering putting the same size tires on the rear that is on the fronts.  What would the ride be like....any less stable not having the extra width in the rear on a trail model?  Also considering going up 1 size to 27's.  I have 1.5" spacers currently.

[2015 Z Force 800 53/Trail EPS]

Because everyone that had gone square has loved it and never mentioned a stability issue, I hadn't thought of that. I have to say other then adding an extra psi or two to the rear it probably won't make much difference. However I have not tested it. I am running 27s with no problems though and if..if I ever need new tires, I will be going square and sticking with the 27s...and keeping my 1.5" spacers on if I can't get the offset I want.