If you can get a hold of a set to test, the way to determine if it'll work with your charging system is this;
Test your charging voltage at about 2500 RPM's. (It'll be low at idle, and that's okay. These charging systems don't do much at low RPM's, that's what the battery is for!)
Install and turn on, to max, heated gear and all accessories you might use during a right (if you ride with your brights on, turn on your brights). Rev the bike to 2500rpm's again and test the charging voltage. If it's more than a few tenths of a volt below the previous reading, then you have too much load and it won't handle it. That said, I think it can handle heated insoles.
There ARE battery powered heated gear setups. If it's a concern, you could always run those!
"8 But God demonstrates his own love for us in this: While we were still sinners, Christ died for us."
Romans 5:8 (NIV)
2006 Vulcan 900 Classic LT "Couch-a-Saki/Mini-Bagger"
2011 Honda Shadow Aero 750 (Wife's)