Very interesting approach there. My main considerations would mostly be: space, ease of transport, 'does it look right?' and so on.
With 1:72nd it certainly looks more correct with BA's rather individualist interpretations of ranges and about the number of vehicles and kind of guns seen on the table.
And yeah, of course if you have the minis it would be silly buying all new ones just because Warlord slap the same logo onto them as onto their rules set to sell that range of minis. By the way: I think the comparison to GW is a bit unfortunate, because WG couldn't charge any more or any way in the same region as GW do because GW sell space pixies. WG sell historical minis, which can readily substituted with minis from any other manufacturer and we all know that pricing in historicals always is different to pricing in sci-fi/fantasy. Comparing their prices to the likes of the Perrys, Gripping Beast and so on would be more in line.
Either way - great idea playing with 1:72nd figures, looking forward to seeing some of your stuff painted!