I heard some chatter about this trick a few months ago on some of the discussion groups, but I haven't had a chance to try it until now. Someone else may have blogged about it in the meantime, but I'm a bit fried today and my search turned up nothing. These are usually the moments when someone tells me that I blogged about it a year ago. That would be funny.
You put some daylighting on a subassembly. Then you realize, shoot, you'd like to use a different type. Today I had DaylightGeneral, but later decided that DaylightMaxWidth would be better.
1. Simply select the subassembly in your drawing.
2. Then right-click on the subassembly on your tool palette.
3. Select Apply Tool Properties to Subassembly.
4. You will see the subassembly switch. Your surface targets should remain intact- at least they did for me. I can't promise that it will stick in every situation.
A few potential pitfalls: It will literally apply the properties including left/right. You will have to go into the properties to flip it over if it comes in wrong. Also, it won't change the name of your subassembly. So if you've left the default DaylightGeneral(4999) or whatever name, you'll be confused. So name your subassemblies something meaningful, ok?
This trick should also work for other types off assemblies. Let me know what you run into.