On my '00 Sprint RS I had the Triumph heated grips. Worked OK, but the off/low/high settings meant I was either too much or not enough. Except for the cost - that part was clearly too much.
So, I installed a dual-star heated grip kit with a heat-troller. Very easy, no complaints after years on several different bikes, much lower cost than the OEM stuff, and fully adjustable heat control.
Here's a convenient installation page from an FJR forum:
I've installed them on a Sprint, Daytona, SV650, and my current Speed Triple. I guess I'm a satisfied customer.
On a naked bike the only issue is finding a place for the control. For the S3, I just stuck the small box to the steering head. It's a little harder to reach, but works fine.