Well as i own 6 esprite and have tried esprite 6, inf 6 and xtream 6 on on a mates, friends comp as he is potty with money and spends like mad, earns to much money and writes freebie modules to improve pc games.
6 Esprite is a cheap cut down version of Inf as i have tried some poser scenes on all 3 programs and Esprite crashes and burns to many times and they made it single core only.
If you want do scenes it was designed for with odd poser figre in then depending size will work nice, butttt the render time is like a snail, as they made 6 Esprite cheapy cheapy cheap cheap as possible.
To be honest its a waste  of money unles you can afford 6 Inf or Xstream.