Old posts, but I had a problem with Draftsight (Version V1R3.1 x64) that might be common to others.
Dell T3600, Win 7, Spacepilot (version 3.16.3), AMD FirePro V7000 (FireGL V) Graphics Adapter
The spaceball work ok when using Draftsight EXCEPT that it was not updating view properly on changes. You had to regenerate (slightly rotating the mouse scroll wheel or moving the spaceball is enough) the screen in order to see just created lines or text. The solution for me was to use the AMD Catalyst Control center program and set "Wait for Vertical Refresh" from the default setting of "Off unless application specifies" to "ON, unless application specifies".
My co-workers without spaceballs do not have similar problems Draftsight, so I assume the spaceball is causing the issue.
Anyway, if anyone has similar issue with Draftsight / Spacepilot, look at vertical refresh setting of your graphics card - it fixed my issue.