Well... I'm not sure if this is what you're looking for, but I also switch between a desktop and laptop at home, so I decided early on with digi scrapping to store everything I own on a portable EHD. Then I just unplug it and move all my stuff to whichever computer I'm using. Of course I scrap on the laptop while sitting at a table, so it's not actually on my lap or I think an EHD would totally get in the way.
I also keep an EHD at work (my offsite backup) and I have an internal HD on my desktop as an at home backup. To sync between all of those hard drives, I use Microsoft's Sync Toy. It's free and it's done the job for me. The only drawback is that I have to remember to click the sync button. I've made it a habit to do my backup on Friday, so I keep up pretty well, and rarely forget to do it.