Read some good things about the Lensmaster that a chap up in Lincs has developed and is now selling at a goodly price http://www.lensmaster.co.uk/
Is a gimbal head just a ball head? Bit of a newbie question but the only time i've heard the word 'gimbal' before is in relation to the SSMEs
Nope, it's a head designed for long lenses so they can be balanced when not tightened up. A good one allows for full and free movement of the lens but when you let go the lens remains approx where you left it.
The lensmaster link above shows the concept.