Basenjis vary, but i would say that those that do chew, really chew and continue to do so throughout their lives. I have always had both varieties (chewers and non-chewers) My Bungwa is definitely a non-chewer but he is a jumper and climber and will fetch things down for Spring and Gbala to chew!!.
I know several people with Basenjis who have leather sofas and their Basenjis don't chew them (although they scratch sometimes) - I have always thought about getting leather but don't quite have the confidence to take the chance!!!! Spring and Gbala's (my worst chewers) sofa is down to the springs - all the stuffing removed and I pad it out with vetbed.
The output from the other end is very pretty though, so that's a plus!! Ha ha!! - before I clear the garden looks from a distance as though full of multicoloured flowers!
Don't let the fact that they might be chewers put you off though because then again they might not!
I once had a prospective puppy buyer laughingly tell me how her previous Basenji ate her Prada shoes - I knew then that she'd be an ideal Basenji owner!