“…In our judgment, generally speaking and in cases where no question of “fresh evidence” arises on an appeal on “proportionality”, a successful challenge can only be mounted if it is demonstrated, on review, that the judge below; (i) misapplied the well-established legal principles, or (ii) made a relevant finding of fact that no reasonable judge could have reached on the evidence, which had a material effect on the value-judgment, or (iii) failed to take into account a relevant fact or factor, or took into account an irrelevant fact or factor, or (iv) reached a conclusion overall that was irrational or perverse.”