Hey Neil - Seeing this late but had to create an account to let you know that the photoshelter uploader is incredibly slow because of all the backend stuff they put in instead of having it just be clean FTP.
To get around this, go to your "upload methods" or "incoming FTP" if you are on brands, and create an FTP for whatever you want, IE "neil1" and direct it to the folder that you would like the FTP to upload into.
Then, Go into photomechanic and select "FTP" instead of photoshelter in the upload panel. Set it up with the credentials you just created. FTP would be ftp.photoshelter.com - Your username - Your password. You don't have to select root or destination folder, as it will upload to wherever you set it up on the photoshelter backend.
This is 8x as fast as the photoshelter uploader and will save you lots of time. I use it to archive all of my raws etc. The only issue is that you have to change the destination on the upload methods panel in photoshelter each time if you are uploading to a different album - but this is negligible compared to the speed you save.
I have attached screenshots so you can see.
Let me know if you have any questions!