Depends on what you want to do in terms of mods.
Lite is basically for someone that would have bought a "chip" in the past. Mitsu MAF, slightly larger injectors, daily driver. Easy peasy.
Full, well it's FULL. More finite map tables, blow-thru SD, external solenoid control, etc. Bigger HP goals than the DD folks.
If you're good with ECU tuning go straight to Full. Otherwise buy Lite, learn the ropes ( ie compare maps to understand changes ), get the car running good, then shoot the moon on mods and update to Full ( nominal cost to upgrade ).