You say that the engine has to be remapped anyways for an SC... that has nothing to do with M Drive. M Drive does not affect the ECU tune, only Steering, Suspension, Stability control, and Throttle sensitivity.
Tech is definitely a must have... M Drive allows for much quicker settings adjustments and you will enjoy MDM mode if you plan to get an SC. It will give you enough leeway to enjoy the car without worrying about getting too out of shape. With DSC fully on, you will be cutting power everywhere.
Remember you also get more throttle adjustability with Sport Plus and a Sport steering setting with Tech. Those settings are not obtainable without the package.
If you were just going to get EDC alone, consider just adding coilovers later on.
M3 Sedan - AW/Black - 6MT - no moonroof - no folding seats - RAC RG63 - clear bra by Omega Werks