I have been playing around with the two grips on my new bat, trying to reduce the weight a little. A little info on weights from my very small sample.
One grip, a scale grip offered most thickness - it added 1.6cm to the circumference of my handle (to 13.6cm). It weighed 43g (1.5oz). I wa sexpecting greater weight, given the thickness.
A Gray nicolls grip was the lightest I found (at Talent Cricket), but there may well be lighter grips. It added 1.2cm of circumference and weighed 37g (1.3oz).
Another two grips weighed 43g and 44g. These were of similar thickness (but not measured), to the GN grip. This range of weight, between a very small sample of grips, amounts to around a quarter of an oz.
I have used some lightweight foam rubber (a sort of mesh, useful for gripping) to act as the lower grip, weighing just 11g (plus a little shoe goo) and adding an additional 0.1cm to the handle diameter, above that of the original (43g) grip. This has reduced the weight by around 1.0 oz. - not earth-shattering, but a useful step in the right direction. Of course, if there was a way to reduce the weight by 1.0oz from towards the bottom of the blade, that would be more significant; with the effect of leverage.
David