well just to throw me pennys worth in...
i have 2 pairs of crescendos 16ohm, 12 A's (72-74 i think), and 4 wem cabs.
now 1 pair is in a much better condition, but doesnt sound as good (stiffer as mentioned before, used less i reckon) as the pair in worse condition..
(well 1 of them i had to replace the dust cap on as when i discovered them in some old cab it had no dust cap and some 1 had put 1 of those clenser pads women use on their faces in there
but it did the job, anyway replaced with a proper ali dust cap with a black felt centre thingy and some slight cone repair round the edges)
..which is a result of them having been played in more as the previous owner said he used it for yrs as a bass cab. so as a result not being as stiff they sound so much better, warmer and not as sterile.
i pair them with some celestion 100w speakers and they sound great with the hiwatt dr103. better in fact than the 73 hiwatt 4x12 i have!
shock horror!
i also like to pair them with some old goodmans audiom something or others, 50w green label that were in 1 of the other wem cabs and that sounds great aswell.
the hiwatt cab sounds great with the head and gives the proper hiwatt sound, but for the floyd stuff i do (and i've tried so many different set ups over the yrs) the hiwatt head with the wem/crescendo/goodmans sounds the warmest/biggest nicest sounding of everything so far, so i think i'll stick with that for the time being.
so in conclusion,
surviving crescendos, having been in all manner of cabs, subjected to all manner of conditions over the yrs, sound different to each other. some sound bad, some ok, some (if ur lucky) sound great. find a pair or 2 mix them with a pair of something else and you will get a great sound with a hiwatt head of course!