B2N2 i think you make some very valid points and you make them well.
I think the mentality of get something as cheap as you can has led to some false expectations with regards bfr time.
At the end of the day whatever intsructor signs your logbook as having succesfully completed the BFR they have to be sure you are competent in all areas of operating in the US. Its their neck on the line too 'cos if the renter does something silly or stupid the first point on the paper trail is the last instructor to sign the BFR!
If i was converting onto a new airframe (i think EAA have diamonds) plus a whole new avionics sytem plus local airspace plus different RT and procedures,plus new notams,flightplans etc,plus the weather both inside the cockpit(xm) and outside(Cb'swinds,often mod low level turbulence) then six hours seems fine to me and speaking personally i think i would need every minute of it.
PS i am not part of EAA and have never flown with them and dont know them at all apart from their website in fact!