C5 pro was the best investment i ever made for $130 in their sale last time, and it can render large scenes.
I asked them whether we will have some capability like vue to do sea scenes as vue is superb but falls down on to many bug's, and don't buy 6 esprite it is a cheap cut down version of 6 inf.
I have had no problem's importing poser 6 stuff into c5 and can get 50% p7 no probs, and it has a bug in 3ds export that is a pain at times on some stuff but buy program it fantastic.
 I have vue through to bryce and certain scenes c5 does some fantastic renders so take the plunge you wont be sorry.