Don't know why but I can tell you this... Futaba 8fg with Naza and R6208SB in hi speed mode is like Rodeo Sex. Have had a couple of rides and it ain't no fun!! Do make sure your R6208SB is in normal mode!! http://manuals.hobbico.com/fut/r6208sb-manual.pdf
SMP... well this is odd. I have two R6208SB Rx, one in Normal and the other is Fast mode. When using the Normal mode Rx the helicam flies like it's drunk. The Fast Rx shows no unusual flying behaviors.