I haven't posted in a long while as I maanged to get my TOS under control. I just wanted to post this in case anyone searches for it.
Out of the ergonomic trackballs, thumb trackballs, foot mice, mice, vertical mice, finger mice and roller mice which I tried (and spent over a $1500 on)
this cheap touch pad I bought off ebay
http://www.ergonomictouchpad.com/
was far the best. No shoulder movement or muscle activation is required. Its awesome. I hold it in my right hand and just use my thumb to navigate.You will need to speed the pointer up a bit. Works for macs too
Hopes this helps someone