Your site’s “Local Root” will have to be reset. You’ll be prompted to do this the first time you try to connect. […] It will no longer be possible to “Go To” any local path by typing it in. “Go To Folder” on a Local path will now bring down a traditional “Choose” panel. […] If you click on a folder outside of your Local Root, you have to manually choose the folder via Choose panel.
This list of changes due to sandboxing sounds like pretty much the best that one could hope for. Panic is lucky to (apparently) not be running into any serious sandbox bugs or limitations for Coda. (My guess is that Transmit will be a different story.) It’s also worth noting that we are saying this now, more than a year after the original sandboxing deadline. In November 2011, I don’t think it would have been possible to sandbox Coda without it constantly bringing up “Choose” dialogs.