The 337 defintely seems quite noisy compared with other twins, I always thought it was something to do with the wash from the front fan going through the rear prop... Contra rotating props make quite a good noise as well, remember the Shack?
Wonder if the Moynet Jupiter, the Do335 or the Rutan Defiant had the same problem?
As I recall 337s were banned from Elstree (while Biggin banned the Harvard...)
I wouldn't call it ugly though...