Dude, for the past 10 years (here in the UK) that's pretty much ALL that us Lotus owners have been buying/driving. The Elise, the Exige, the Evora, all supercharged (with some NA variants). None of the later supercharged Lotus are easy or cheap to tune. If you think that a bolt on power upgrade for the V6 is going to be a few hundred dollars I'm afraid that you will be sadly disappointed.
Turbo cars? Lotus have a bit of recent history with the VX220 Turbo - mapped to give a virtually flat torque curve from 2K revs upwards - I'm expecting similar from the i4.
Finally, there's no bad choice here, they will both be great