What year is your bike?
Post-'01 bikes do a better job of maintaining voltage throughout the RPM range than the early bikes but don't have kickstarters. If the load exceeds the charging system's ability to replenish the battery you could wind up afoot, particularly after short trips or low RPM riding.
A small voltmeter would help you monitor battery voltage as you ride. 24W is a substantial load, but you could switch it on and off according to the volt meter if it affected charging.
It's a 2006. If I ride with a voltmeter attached will it tell me how much extra watts I have, before I purchase the gloves and install them?
I believe the temperature controller has 5 settings and an on/off. Would I be safe to assume that the listed power usage on the gloves, the 24 watt draw, would be at max settings or do you think it would be consistent?