Much of the differences are the arm cart and plinth all things being equal ie good idler drive good belt and good DD.
That said no belt I ever owned sounded as good as the Commonwealth or as good as one of my SP10mk2s or indeed my G.
That does not mean there are not great belt drives that will equal or come close.
Re the 401, they are a good turntable, I have serviced many, but the motors, bearings ect do not come close to a Commonwealth. If one came up at the right price I would buy one just for completness (I collect turntables), but it would be with eyes wide open re limitations.
Chris