There is no avchd export, never has been.
Match sequence settings means you get the codec used in the sequence which means a preview codec (usually I frame only mpeg, and of lesser quality)
If you want to add noise reduction (I assume video and not audio) before editing then use a intermediare codec like Cineform which is now available in PP.
I do not use dnxhd so I cannot comment on that.
DNxHD is an intermediary codec like pro-res and the Ninja records it in a Quick-time wrapper for use on a PC. That doesn't make any sense, does it? Why Quick-time and not AVI? Premiere exports it to XMP, whatever that is. I just don't get it. The idea is to pre-process the clips and get them back on the timeline in the same format, but it's not possible.
So, what should be the workflow, then?
I suppose there are plugins available. I think Avid used to have one for DNxHD. I would think it should be part of Premiere by now.
I am having the same issue as you. I need to clean-up my AVCHD footage shot on a dslr Canon 60d and bring it back into my Premiere timeline. So confused as to which intermediate codec to use and the workflow. I've been playing with DNXHD175X 10-bit to help avoid banding, but not certain if I am going in the right direction. Did you figure out your workflow and if so, could you please enlighten me? So frustrated!
Thanks so much,
I use that very DNx option myself for all my footage. It edits beautifully in PP, much smoother than the original.