I think there's been some discussion of each community having their own community, but no decision's been made.
I certainly had assumed that there would be a comment period run through the ICANN website, like most (if not all) of the other implementation contracts and other documentation relating to implementing the transition. If you look at the ICANN public comment page at
https://www.icann.org/public-comments, you'll see 2 open public comment periods, as well 3 recently closed public comment periods, relating to the IANA Transition. It would be an odd outlier not to have a transition-related comment in the ICANN public comment system.
The ICANN public comment system is transparent -- the comments are announced by ICANN, each "comment forum" (to which the comments are submitted) is publicly available and stays publicly available as an archive (you can find comments going back years, if you want). You can see and read submitted comments in real time.
How we deal with the comments after they're submitted is a different question (typically, ICANN staff collates the comments into charts and/or spreadsheets, often with a summary -- the exact process is figured out based on the nature and extent of comments.
Whether we do this only from the point of view of the names community (and other communities do their own thing), or this serves as a central comment repository is also something that needs to be discussed.
I went looking for the IETF Trust comment infrastructure. I did find links to three public comment periods on the IETF Trust home page at
http://trustee.ietf.org/. Two of these link to pdf pages that request the comment. One provides the trustees' email address, while the other does not say how to submit the comment. The third one links to a text page requesting the comment, this one also does not say how to submit the comment. I don't see a public repository of the comments received, or any public summary of the comments received.
Overall, it seems from what's available that we're best off using the ICANN public comment tools for this process, based both on its use for other transition-related comments and on the transparency of the tool in question.
Greg