in terms of weight...I guess if you put a leather grip vs a synthetic replacement grip, you should find that the leather grip weighs a little more...
however, is that weight differential so great that you could "feel" it whilst swinging or is it so great that it you could "feel" that it considerably affects the balance and swingweight of the racket, I honestly do not think so....but that's just my opinion...
A few months ago, I decided to try using a leather replacement grip with a Wilson Pro overgrip...it took about half an hour to get used to it...because it actually does give you more feedback upon ball impact compared to a synthetic replacement grip with an overgrip...mainly due to the synthetic material "absorbing" much of the feedback...
If you actually appreciate the feedback...then yes you would like it...
Personally, I will stick to leather replacement grips forever!
the downside is...the harder handle/grip may give you problems with calluses...