Ah yes, 'numb bum' across the pond would have a different meaning, try 'numb donkey' (I don't understand the merikan predilection for asses), it doesn't rhyme though
I have sat on a B5 seat, it doesn't have the same firm flat cushion of the C5 solo seat. A number of small/one-man companies abound that will re-cover or re-pad a bike seat. The C5 solo seat does have a reputation on being the best seat yet to come out of Chennai. Problem with a seat breaking-in would be the cushion crumb breaking up or rotting.
Sinking into a soft cushion puts pressure on the tender parts, it's supposed to support the ischial tuberosities (sit bones) that are equipped to take one's weight, not allow them to sink in and put pressure elsewhere.
H do offer a few alternative dual seats for the B5, any of the english ones will have better padding.