I was thrilled to find SME as a potential solution for pulling together cloud storage from many providers and for many projects.  

For the Linux Tools, here is what I have found:
  1. The sync tools is very, very slow, at least with a Google Gdrive account, compared to uploading folders via a browser while logged in to the GoogleApps account.  CPU and network use do not seem to be an issue (Gbit connection).  If there is a fast way to get files to the cloud via SME, I would like to know about it (e.g. upload to the SME AWS and then copy to Gdrive).
  2. Because SME does not touch content, only metadata, I would gather that sophisticated algorithms such as that used by rsync for only sending changed blocks, are not possible.  Only full file upload/download is possible.  
  3. I could not find documentation about how the sync tool determines whether a file is out of date or not.  Time stamps?   Upload of folders through Google's Gdrive GUI resulted in replacement of the modification date from the local file structure, which I need to maintain.  An SME sync after this direct upload would result in the entire file structure being downloaded, wiping out the correct modification dates for individual files.
  4. Very strange behavior with the Fuse-based virtual drive.  This has the promise of command line manipulation of the file system.  However, it behaved strangely, only revealing part of the file structure.  I would visit part of the file structure and recursively list (ls -lR)  and directories would show 0 entries, even through the cloud store has files in those locations.  If I  then go to the Sync tool and expand the structure to one of the directories that the virtual fuse mount  was empty, so the files contained there appear in  the GUI, then the virtual file system will recognize that there are files and show them.   I was hoping for something like occurs with Wuala, where the fuse-based files system shows in its entirety with a large persistent cache.  Local syncs are fast, and then slowly propagated to the cloud.  

Thanks for the feedback.

You should check the latest version of the Linux cloud tools as they are a few iterations on from what you checked and there are a number of performance improvement as bug fixes there.

I will check out the latest cloud tools.  Thanks. I have had some back and forth with a trouble ticket regarding the date stamp issue, and first glance has the problems still remaining, but I will take a more careful look.   Then report back here.
Quote: However, it behaved strangely, only revealing part of the file structure.
Probably, folders was empty, because list of that files was received from SME (not from Google Drive provider).
There is one difference between Sync Center and Drive. Sync Center always take list of files from provider. The Drive by default take list from SME.
So, if you uploaded some files or created some subfolders directly in Google Drive (without SME) then you will see it in Sync Center, but they will be missing in the Drive until folder refresh or provider resync.
This can be fixed by turning on option "Real-time refresh" (on the site in Dashboard).

Keep in mind that Drive keep list of files in cache 30 sec. (it can be changed in the settings) So, if you upload file directly to Google Drive then it will appear in Drive only after 1-30 sec.