I have Oxford grips and they work great. Four levels of selectable heat, only $60 (on ebay) and easy installation made them an easy choice for me.+1 for Oxford grips. Zero issues to report after three years of use.
I have the Oxfords run with a variable controller. Excellent. On high, they will cook your hands. Easy to install in the winter and remove in the spring. I plug them into the accessory leads so they shut off when I turn off the bike.
+1 on the Oxfords......and "WHY" would you ever take them off?
I've got Hotgrips and love em.
http://www.hotgrips.com/store.php?rn=121&action=show_detail