With 8gb already you will notice absolutely no difference at all.
I did exactly the because the ram was so cheap but to be honest its made no difference what so ever to me personally.
But is that down to the RAM? Are you monitoring your usage? LR can stutter a little in places regardless. I edited for years on a box with just 2GB of RAM. I recently upgraded to 12GB of RAM and yes it is better but not a six-fold improvement.