So after our conversation Andy I did alot of reading and looking around and my conclusion is the drilled and grooved disks will only benefit you if you're driving at high performance levels, and for typical Freelander type driving - on or off...
How long is a piece of string?
You’re looking for an alternative to a disco, but you rarely tow and rarely go off-road? So you could, in fact, have any car you like or can afford.
Sod it. I'll put a pair on and see what happens. Checking pistons are free in process.
The 18" wheels are so heavy, just taking them off once is very attractive.