I am using this with my upright bass and my fender precision bass.
first for upright: it is definitely useful specially that you can cancel feedback from it . in terms of control, it has a ton of feature ( too many buttons for me ) but definitely has many usable sounds but need a lot of experimentation as it is not straight forward i think.
no cons really when using upright bass , except the fact that theres, deliberately , no volume control when using as DI. well ... otherwise , you just need time to experiment.
when using the P-bass, i didn't love it , it doesnt harm but it didnt see how it adds. that probably because i expected more to the extent that i would be able to make my Pbass sound like an active bass or a possible better slapping sound but it wouldnt do that ( analog preamp!) heard it can make an active sound passive though - didnt try .
I would buy it for upright. and for recording with upright.