My guess is that the E7SE will not leave much room for upgrading. I imagine KDE must hate it.
Also, the E7SE metal tail slider should be adaptable to the E5, so not much room for upgrading the E5 either beyond that, except for maybe the battery tray, but Ralph already took care of that. The E5 can be stretched to E5s, and the E7/E7SE can be shortened to a E6, so not reason to waste effort on a specific E6.
There are lots of 3S 450s in the market, so Matt may not want to waste his time competing with that market.
Since Matt is an entrepreneur, I can only deduct that he must be working on a high-end 450 and/or 500 size kit designed to run on both 3S or 6S for customizability and with a TT tail drive. That unique design along with the current popularity of the Synergy brand would corner the market for at least 8 to 15 months till the clones catch up.
I imagine that virtually all loyal Synergy customers would buy it, even those who would other dislike smaller helis, even if just for completion of the Synergy collection. It would also be a nice natural progression for folks who are happy with the very popular RTF Blade 450X, but want to undergo the experience of building a real kit, but don't yet feel ready for a larger and more expensive helicopter.
My crystal ball says the Synergy E4 will be available by Thanks Giving 2013. I guess only time will tell.
