The clutch turned out to be fine, no adjustment was required.
I have spoken to a couple of friends and they don't think that it is the clutch that's causing the problem. When I told them that the gearbox is cable driven, they immediately said that, that is probably were the problem lies.
From their experience cable select gearboxes are very difficult to get right. I haven't had a chance to look at the system. If someone else has adjusted the cables I would be grateful for any tips on adjustment. I would really like to get this sorted as its now becoming very annoying, if all else fails I guess I need to take it back to the dealer.

 

I read on another forum that Mazda specifically designed the gearbox to have a very rwd feel. Heavy shifter cables transmit the feel of the synchros directly to the shifter. The 240 has a pretty stiff feel to it but since that is the car I learned to drive standard on I didn't really notice the difference with the 6...except it was much smoother. I drove a buddy's acura and that thing was like butta, but I could hardly tell if the car was in gear or not.
My $.02

 

Here lies the problem with your shifter:

Your vehicle is a front wheel drive car. The engine sits East/West, not North/South like the engine in a rear wheel drive car does. Therefore your transmission (ie transaxle on a front wheel drive car) is not located directly under your shifter handle like in a rear wheel drive vehicle where the shifter handle goes down directly into the transmission case itself. Beause of this drivetrain configuration (front wheel drive) your stick shift is connected to your transaxle via a metal cable system. By changing to a short throw shifter you will NOT gain any better feel/directness. The poor feel that you are talking about is not because of your syncro's, but because of the cable system that links the shifter to the transaxle. This condition can also improve or get worse depending on weather conditions. I bet in the summer time when it's nice and warm outside, you will not see any problems. If you have problems rear round you may have too much free play in the cable system (possibly at the end links) and should have it checked out and adjusted.

 

That would explain why some days feels better than others

How do you explain the buttery feel of my Acura I used to own which was a FWD too ?

 

Is the UK 5sp gearbox the same as the US spec?