I've currently made two versions of the map: A Mech only Solaris Arena version to focus on close-quarters combat in tight spaces, and a BA only Team Solaris Arena for all the little BA players to frolic in. Since I've just realized the .cry files for the original Crysis Wars maps are actually included with the game (hurr), I'm currently in the process of taking that original map and redesigning it for the BA-only TSA map (It has some nifty little areas that would be a pain to restore manually, and the process should be a quick fix-up). The SA map, which is based on Pytak's (T)SA version, is basically finished, and I'll release both at once some time in the near future.
TBH, BA really aren't all that OP in the Solaris Arena version from the times I've played on it - it's just that it's far too tempting to run around as BA in a setting perfectly designed for that unit, and I wanted that map to focus on the difficulty of properly manuvering a Mech in such confined spaces. Hence, the split into two different maps.