The Steps
A quick google search didn't reveal a how-to, so I'm volunteering my own. It's actually really straight-forward, so the post will be relatively short. Unfortunately, I couldn't find a way to do all of the lists at once, but I can do an entire list at a time.
- Create the list you want to move in Remember the Milk, you can do this by going to Settings > Lists > Add List.
- Switch to the info tab in the settings, and copy the "Import Email Address"
- Expose Google Tasks in GMail by clicking Mail in the top left and select Tasks.
- Switch to the list you want to transfer.
- Click on Actions > Email Task List
- Paste in the copied import address in the To box
- Remove the list name from the body of the email
- Send
I'm pretty sure notes get lost in this process, so you'll have to keep the google tasks around long enough to transfer them over. This wasn't a big deal for me, as I didn't use that many notes before moving, but I could see that being annoying if the feature was used extensively.
The Reason
I decided to switch back to rtm because gtasks was just too simple. I'm not looking for really complicated features, but entering tasks was getting frustrating. I also got sick of looking at the tasks in tiny windows on the side of my calendar and mail, and remember not having that annoyance with rtm.