Nah, I'm a Big Spender--on this route I'll go the "luxury" bus and do the $2-2.50 an hour with slightly less time. I did the Sorya bus between Kampot and PP and my tookus was rather underwhelmed. On the other hand, the PP-Battembang and the Battembang-Siem Reap buses were quite comfy though I can't remember the companies (definitely not Sorya).