I had the Oxford Adventure heated grips (slightly longer than standard) on my previous bike; a Yamaha Super Tenere and I couldn't use them on "100%" as that would have burnt the skin off my palms; 30, 40 or 75% was fine in the sub zero riding I did in the States. They are apparently fairly easy to fit but had a relatively large control panel bolted to the left handlebar/control, in comparison the Honda control is unobtrusive in design.
I personally find the Honda OE heated grips are fine for me, I've not use the bike in really cold weather yet and when I have had cause to use them, they were more than adequate. I do have a good pair of gloves so that must have a bearing on the matter, but no hand guards, as yet. I think you pays your money and takes your choice.