Ditto - if you were moving from Snow Leopard then I'd recommend a full separate disk backup and install on the new drive. However because you are already there then there is no need!
Be sure to get some fast external storage for your media drives though! Thunderbolt or FireWire 800 RAID.
I really like Lion and have been using it since it was released.
Also there are number of ways to use both FCPX and FCP7 in the same work-flow so don't worry about what you need or want to use.
For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]