That being said, in my experience, heated grips that have the heating element built into the grip itself work much better that the kits that you install underneath the stock grips.
You can say that again. Big difference. Ive got Heat Demons under my Kuryakyn grips on my Can Am Spyder... I thought they were the shit until I installed Oxford grips on my fz09. Holy hell they get hot Im telling ya.
The convenience of hand grips offsets the lack of efficiency. You never leave them at home, youre not wired to the bike, no wires running up your sleeves, etc, etc. Youd be surprised how often you might use them even in the summer.
Now I have some heated glove liners for the serious cold with the Y cable running up my jacket sleeves. A pain in the ass really compared to heated grips but its more warmth. A trade off.