Chances are, one way or another, you’re gonna have to transcode your native footage to DNxHD before you export from Media Composer.This is true for certain FX or exports to Quicktime reference. So, importing AMA and transcoding within Avid MC is just one way to do this.
There are alternatives which allow trancoding to DNxHD before importing to Avid, then when you import, Avid will do a “fast import” which isn’t transcoding, just re-wrapping the mxf file. My favorite methods incluse pre-processing in Adobe Media Encoder, TmpgEnc, or Adobe After Effects. AE is a good approach since you can do some stabilizing or sharpening in AE before the fats import to MC.