Focusrite's 2i2 ($149 retail) will record into the Sero HiSense Pro 7 ($149) tablet using a particular cable that costs about $7. I tried it and posted about it on TS a few months ago.
From what I have read, the ability of an interface to work with a particular tablet is still very product specific. I would want to know that the interface works with the particular tablet or specific device I intend to use before spending my money.
My hazy recollection is that the data connection between the Focusrite and the Hisense pro used up the port that would have been needed to use an external battery. Although the battery life on the Hisense is something like 6 or 7 hours, I didn't try to determine how long the battery would run providing phantom power through the Focusrite.
The advantage of the mixerface would be its built in battery and being physically smaller, but is it worth the extra money?