Regarding the "Mum" thing, I think it worked much like it works when Scott challenges someone on their character, it forced Claudia to come up with something better, and she very much did that.
I do like the presence of musical guests in general. They definitely have a different energy from comedy vets but I don't mind a bit of actual reality in my CBB cocktail. I loved Aimee Mann's presence in the early episodes and she didn't tend to do much other than tell anecdotes and the occasional dry remark.
Although there was this great exchange after a meandering conversation that had touched on the Olympics:
Scott: "What do you think about the separation of Winter and Summer?"
Aimee: "I think it would be hard to have those two concepts at the same time, Scott."