I don't own an e92, yet, but the whole premise for buying that car is that v8. (of course the chassis and looks count too)
M3s will always have that balanced chassis, good handling, and practicality. But, as the newer cars come out, the M cars are losing what made them awesome in the first place, the MOTOR.
The new M cars are giving up the unique built 'special' engines that are powerful naturally aspirated and high revving for engines that are basically more powerful versions that are already used in other models, other 'normal' models.
What will make the next M3 motor THAT much better than the next 335i? (other than power output, which can be remedied just like people do now with turbo engines)
I am sure the F80 will elicit some awesome reactions, and I am sure that the lag will be minimal, but still. It will NOT have the same feeling as taking a NA engine high into the revs. Ask anyone who has chipped, tuned, and modded out a 335i. It is still not up to the same experience as the engine in the M3.
just my opinion of course
edit: oh yeah, forgot to answer the op
Yes, I would/will pay more for the v8 M3 in years to come, because as you stated, this is the last NA M car, the last and only M3 V8, and it will be missed by enthusiasts.