Here Q1-01 is showing off his cargo bay, quite possibly big enough to smuggle Yoda in relative comfort.
He could also be fitted with a balistic weapon in this bay such as a mortar launcher. Again the four legs come in handy, providing a far more stable platform than any other astromech, even compensating for uneven ground with his extendable legs.
He can also bow better than R2 ;)
Or curtsie anyway...