Grip Weight Impact

I am curious as to what effect lighter grips will have on my irons?  I am considering a Golf Pride VDR undersize grip that is smaller and 1.5 grams lighter than the Golf Pride Standard Size New Decade Multi-compound grip I currently use.

Little to no difference making the swing weight heavier. It takes 5 grams at the grip to change one swing weight.

Something like switching from a Golf Pride Tour Velvet (52g) to Excel RF Standard (42g) makes a difference of 2 swingweight points.

The spread between Tour Velvet Midsize (63g) and Excel RF Midsize (43g) is 4 swingweight points!

Dri Tac Lite (23g) or Golf Pride 25 is a HUGE difference (close to 6 swingweight points with the Dri Tac vs Golf Pride Tour Velvet).

I have a pretty upright swing so my 910F 19* is 41" with Surefit at A3 (+1.5* upright lie angle) and I use a Dri Tac oversize grip).

I learned this with TM clubs because they are horribly long (my driver is 44.5" and stock length is 45.75").