I've got heated glove liners and have also used heated grips on my previous bike and I'll take the convenience of the grips on a bike any day of the week.
My Koso heated grips are waiting for me at work where I got them delivered but I've used the liners on the last few rides and here's the routine I go through:
1. Make sure the batteries are charged.
2. Put the batteries into the pouch that goes where your wrist is.
3. Put the liners on and fight with the battery pack pouch to barely fit under the sleeve of my jacket.
4. Put my motorcycle gloves on over the liners.
5. Hope I didn't forget anything that requires my bare hands or I'll be doing it all again.
When I get to a spot I want to pull over and have a coffee or whatever, I need to now reverse the process and have the liners to carry around besides the gloves and helmet (stuff them all in the helmet).
Get back on the bike and it's # 1-5 all over again.
For a bike, the grips are just way more convenient. However, I have used the liners shoveling snow on a bitterly cold day or skiing, etc so they have their place and I'd still own a pair anyways but on a bike the grips win easily for me.
These are the exact pair I have here: