the unit from tech-aero does look good. I havent seen one or used one though so cant comment.

I too just prefer to use seperate batteries, 50cc and above planes dont suffer from an extra4 cell pack weighton the ignition anyways. Maybe smaller planes could benefit from it doing away with seperate batteries, but at what risk? I do use opto kill switches though. wouldnt fire up a 50cc plane without one.

we also used to fly large planes on Nicads, wouldnt do that anymore ................so the time will come where maybe we can use only a single battery