Understood.  If that would be new behavior for uploads (in general), my vote would be to skip it for now. :)  It looks like libcurl has CURLOPT_FILETIME to get at the mod time via SFTP now, but size doesn't seem to be implemented.  Although from this it doesn't sound like it would be very hard for someone to add:

https://curl.haxx.se/mail/lib-2011-01/0094.html

Thanks again... liking the app :)

Would love to see this also! Just bought the app tonight and TBH I sort of assumed that's how it operated for SFTP remotes.  (connect then just edit/save)   At the moment that's what will keep me in Coda, as I'm often working on Node projects (running via Nodemon or create react app) where I just want to quickly edit remote files and see the results as I go.  Hopefully libcurl will work out for you.  Obviously it can upload files currently, but it sounds like you may be looking to do something more sophisticated than just uploading on "save"