Simflea
All aircraft are designed to flex, otherwise they would crack and fall apart shortly after you got airborne Concorde used to strecthc something ridiculous and the effects, allegedly, could be seen in the rear toilet). The wings on the MR1/MR2/MRA4 do not meet (sic). They are each bolted (fwd and rear spar each side) to the frame of the No1 Tank. In the case of the finlets on MRA4, don't matter whether you are convinced or not, they work for the aircraft. Only time will tell if MRA4 is going to be a stayer or not as you put it but I can tell you if given a choice between MRA4 and Mr Boeing's effort of an MPA, I'll take MRA4 every single time, no question.