Wouldn't this work:
Define the Palm Desktop to be the iSync device. Then HotSync would sync Palm with Palm Desktop. And iSync would sync Palm Desktop with Address Book and iCal (and other devices).
In that way, you wouldn't have to give up any of the functionality of your Palm or of Palm Desktop, but you'd still get all the functionality of the Apple products.
Why wouldn't that work?
Yes, it would add a bit of complexity for those who don't care about those extra Palm features, but just a tiny bit.