There's no reason to use AE, unless you need to some complicated compositing or VFX (motion tracking, 3D, image stabilization, 'fake' slo-mo, animation, etc.). And even if you did need to do stuff like this in AE, you still probably want to come back to Premiere for final edits (Premiere is made for doing final edits, AE not so much).
I would recommend:
- Mount your MLV files with MLVFS
- Load CDNG sequences directly in Premiere
- Either grade in Premiere (the tools are actually decent if you learn how to use them), or "Direct Link" to SpeedGrade
- Edit in Premiere (jump back into Sg at any time to do more grading)