Gentlemen,
Things are still moving very slow with SMA these days. The French are very methodical in their way of thinking and I have found over the last few years that their short term goals equal to American's long term goals.
Having said that the current hold back w/ regards to further development are as listed below.
1. SMA claims that this engine was not designed to be a pusher, and further engineering will need to be accomplished in order to change this. I'm guessing it’s a bearing issue of sorts.
2. Available aircraft/interest with the current fleet of existing 337's versus the cost of which would be involved for this type of mod, vs. the potential payback for millions spent for the development of the STC.
Not easy questions at this time but there is renewed interest by SMA and we are talking to them about this in the very near future.