Im about to install 1/2" x3" Brazalian Cherry over concrete. Your website recommends 3/4" CDX plywood for the subfloor but was wondering if I can go 1/2" plywood since my hardwood is 1/2" . 1/2" hardwood + 1/2" plywood would raise my floor by 1". 1" is the max I want to go because I will be installing ceramic tiles in the other room and I dont want a big drop in transistioning between the hardwood and ceramic floors.

Why not gluedown a quality engineered wood, over the concrete?

Are you dead set on a stapled down solid floor? If so, 5/8" CDX is the minimum recommended.

Make sure the fasteners don't blow through the plywood and puncture the moisture retarder, under the plywood.