drseti, The orice differential between the nonaerobatic IO-233 and aerobatic AIO-233 is rather low.
The two fundamental differences are a beefier crankshaft and the inverted oil system. The inverted oil system consists of a different sump and some changed oil journals in the case. I don't know what the price differential between the carburator O-233 and the IO-233 are at this time. The carb hanging down underneath would spoil the lines of the Comet cowl anyway!
The first aerobatic engines are ready, now all we need is the two airframes which should be ready to ship soon.
The initial aerobatic envelope will be limited to basic loops and rolls. We will conduct an extensive aerobatic test program to expand the envelope with emphasis on spin recovery and aerobatic weight increase. The additional weight and power of the Lycoming up front, will improve the recovery characteristics and vertical penetration. (IMHO) The FK-12 was never intended for unlimited type aerobatics. However, it will be capable of some very nice "Gentleman"s" aerobatics.