I forgot to add my review of Marco Dewa to this thread from my visit on 02/2010
Marco:
* Replied to email within one day
* On time at DPS and waiting for my arrival
* High quality, clean and air conditioned Toyota van
* Spoke very good English. No issues with communication
* Courteous and very flexible in accommodating my requests
* Deep knowledge of the area that enriched my tour of the island
* Affordable and thankful of my business
A+ all around and I'd use him again on a future visit.