I'd not want it to be the primary Time Machine backup, if it were to offer that option. I might still have that as backup of the backup if it has the option. Otherwise, the lovely thing about the Time Machine is that I can fly-by through time to get back the work I was doing and hand-pick back the version/section that I want.
So, I usually stick a cheap HDD to the Macs. For travel, the small SSDs have such tiny foot that I just let them be around. I set-up a 1TB HDD for my daughter and she thinks I do magic when I had recovered her works a few times.
