I'm not sure. If your goal of carrying your data with you is that you don't trust it to stay secure on a system, then plugging in your USB stick to the computer seems like a security risk right there. Once you decrypt it, another person could have some kernel stuff running that grabs all your home data at that time. If you trust the box, you may as well leave your data there with regular encrypted home folders.
For the general idea of you having multiple computers and wanting to use the same home folder on each of them, then the encrypted USB stick would be a nice safeguard against accidentally losing said stick (prevents the finder from reading it. As if even 1:1,000 random people would even be able to read a UFS or ZFS stick :P - of course, you should still encrypt anyway for that case.)
I think your second use case is probably the intended one. E.g I have several computers at home and work that are all "trusted" and I want to conveniently plug in my home directory on whichever one I'm using.
For the general idea of you having multiple computers and wanting to use the same home folder on each of them, then the encrypted USB stick would be a nice safeguard against accidentally losing said stick (prevents the finder from reading it. As if even 1:1,000 random people would even be able to read a UFS or ZFS stick :P - of course, you should still encrypt anyway for that case.)
Still a cool feature though.