I am a beta tester for SureFly. After about 50 hours or so on a single unit I went dual EI. I have 2 completely independent electrical systems and feel very comfortable with the setup. I now have about 200 hours total time on the SureFlys. Never had a problem with them and fuel burn, LOP operations, and starting ease have been as described above.
RPM is sensed off one unit, therefore the only squawk at present is that with 2 units RPM drops to 0 when the sensing unit is turned off for mag check on startup. Had the same issue with my Slick/ElectroAir combination on my RV6 and it worked that way for 14 years. They have a fix for this for me to try.
When I installed the engine on my 10 the PMags for a 6 cylinder “would be available very soon”. That was 6 years ago.
RV-10 and Breezy