I bought 16 armoured pikemen from The Assault Groups renaissance German range to bulk up mu Pirazzos Lost Legion and they fit perfectly with the GW models, both in scale and detail. I would happily recommend them.
Also I've just recieved 8 "greatswords" in the post from Artizan, along with some pikes for the Lost Legions addition, I think they'll fit in reasonably well with GW greatswords however my unit is entirely made up from the Artizan models and they don't look out of place or too small amongst my gw minis.
I'll post some pics if I get the opportunity.