I have been using SW since 97+ and never missed a version until 2005.
I missed 2005 due to my ex-employer dropped subscription. Going from
2004 to 2005 was not too painful for me as an individual, but I found
the learning curve to the new version was much longer than normal,
because I had to learn what was added and changed in 2005.
There are usually minor issue when switching versions, in my experience
those issues can be much worse if you were to skip. Especially with
assembly mates. (Has happened in the past).
IMHO SW 2006 has been a pretty sucessfull and solid release, although I
did not start using it before SP1. The assemblies do perform much
better, I think they finally got 'Lightweight' right.
In a nutshell personally I would not miss a version again.
Who knows how long it will take to get 20 seats up to speed with 2007.