No idea about the actual weight difference, I didn't bother to weigh it prior to drilling the holes.
If I can get motivated to finish it this week I'll take it for a run against the ball machine on the weekend, but there's no change in performance going by the very scientific method of bouncing a ball on it.
This one feels 'right' in the hands though, much better than the one I got engraved which I suppose is due to the reduced weight and thinner toe.
I've asked the guy who did my Tusker reproduction stickers to see if he can make the Puma/Millichamp ones.