I tried to migrate directly to 3.0, but ran into display / override problems w/ Joomla's native Contacts component, so I went back to 2.5, again using SP Ugrade. And again it took me less than 30 mins to migrate everything!
Especially, I like the idea that SP Upgrade manages the core stuff for you, and then it has the capability to copy over custom tables (in my case to use with Breezingforms). Worked like a charm!
5 stars obviously!