I am looking to upgrade an existing spinning reel setup.  I currently have a 6'6" St.Croix M rod, and would like to get a new spinning reel.  I am looking at the Revo SX spinning, but I am a bit confused by the sizing.  If I wanted an SX in a similar size to a Shimano 2500FJ or FH, what would be the equivalent in the Revo?  Would it be the SX-40, because they have similar line capacities?  Any help is appreciated. 

I had a similar question awhile back. What was imparted to me was to compare line capacities between brands. That should give you an idea of comparable sizes between brands.

http://www.bassresource.com/bass-fishing-forums/topic/109698-spinning-reel-sizes/?fromsearch=1