I have just received a parcel from Paul, containing a set of ECW sprues (as well as the two emperors (okay, one dictator-for-life and one emperor, for those in pedantic mood). I have to say that the ECW sprues are gorgeous - the plastic Romans were (and are!) very nice, with the Celts a step forward in anatomy and detail; these take another stride forward. The detail is to die for - anyone who says you can't get as much detail on a plastic figure as a metal one should have one of these sprues superglued to the end of his nose so he can't fail to see how fine the detail is.
Size-wise, they appear to be 27.5mm sole of foot to eyeball, so they ought to fit pretty well with the Perry and Foundry figures.
Those who are fussy about having all the figures in their units in similar poses (advancing, charging pikes, loading or firing muskets) will probably want/need to mix the contents of several boxes into different units to achieve the sort of uniformity they're after. I am not, I probably ought to confess, that sort of wargamer - 'untidy' is fine by me - I can't see most drill surviving long in the push and shove of an ECW melee.
I had been going to make the Peninsular War, using Victrix's figures, my next project, but I am sorely tempted to change my mind and do the ECW instead...