iirc the NTFS-3g for Linux is a kernel module, so it may not be able/difficult to do with the stock thecus version of linux installed. There is a guide on how to get Debian on the thecus 2100, that maybe your best option.
I did some performance measurements with the latest ntfs-3g version 1.2129 running data transfers from an NTFS formatted 400 GB USBHDD to the internal harddrive. Read performance is around 6Mbyte/sec whereas write is around 1 Mbyte/sec with the CPU at 100%. Tests has been done transferring a 1Gbyte file.
Yes, it could be done, but there are two very good reasons not to do it. First, the utility ntfs3g.probe is only two weeks old and second it does modify same basic paramters on the disk. An operation which I consider rather dangerous since it is not reversible.
Maybe adding a button on the options page of the module would be an alternative.
META script mount_any_usbdrive.sh.off does use ntfs-3g.probe --readwrite to decide if the ntfs-3g driver should be used for mounting. If the probe returns any warning or error the mount process is handed over to the default mount statement.
If your ntfs drive fails to mount in read-write I would recommend you run a filesystem check on your PC