Thought I'd cast my vote
I would say that the Rango 410r does not really need the optional alloy, the only thing which has been commented on in the Rango thread has been the plastic pivot blocks but all the same it's very robust & has gained really good results as it is without forking out £££, on the whole it's really good value for money...
Little knowledge on the Bmax as I've never run one.
Both run saddles so no issues there