a big box with legionaries and extra sprues of special poses is really a good idea. Street-working, Priests with a sheep, casualties etc. Something I would like to see. And of course the same for Roman's enemies!
I would need (at least) 5, better 10 different Roman Big Box sets, to depict the most famous emperors and Generals with their staff and court, Roman civilians, merchants etc. IMHO, every army needs a decent command set and I must have 10 Roman armies with hardly any central command.
Why not run the set in two or more differnet colors, so if we don't get a similar set of opponents, we can always fall back on the old RCW.
I would also like to suggest that Strelet's also borrow a good idea from Hat's Alexander range, and do a Roman Army set, consisting of one single sprue from each of the Roman sets. You could do this for the Normans, Moslem and Nopoleonic series too.