Whether or not to use 3.0 over 2.1 depends on a couple of things.
the main enhancements to 2.1 (that I recall anyway) were:
1) Transmission line description of packages (instead of lumped LC)
2) Multi-Driver specification (literally a driver that has multiple
stages that turn off and on at different times, like an early kicker).
if you don't need the above things (or some of the other changes) or if
2.1 is already giving good results, then you probably don't need to
Another issue to explore:
When will the EDA companies be supporting 3.0 ?(which probably is
coupled somewhat to when 3.0 is officially opproved by EIA and I am out
of the loop on that but I'm sure someone will comment when they read
I recommend bouncing your question off email@example.com for a more targetted