Boss newbie lang din po ako. I choose 508 kasi base din po sa needs ko. I don't need video upscaling features kasi for NMT and my lappy CQ40 HDMI naman w/c is pwede na even video repeater lang like 508. And I think the price difference between 608 and 508 is more or less 10K w/c is dagdagan ko nalang ng konti makakabili nako ng PS3...hehehe
I am a proud owner of an Onkyo 608 and I am satisfied with what I paid for. But as ShogdGreat said it depends upon your need and budget. The 508 is really an upgrade to the previous 507 with its added features. I also chose between the 508 and the 608 when I was upgrading. Maybe it was really because of wanting to purchase a 607 before the new products went out that when I decided and saw that the difference of the 607 and the 608 is very minimal I got the 608 na.
I suggest if you have the budget at 31k then go for the 608 and its other features, for a THX certified reciever this is very cheap and you will have options you dont if you use the 508. If not and you decide to use the price difference for you to buy a set of very good speakers to go with your 508 then that is also great. This means you can balance your budget on a good reciever and a good set of speakers and sub.
Once you decide, always think that you purchased the best para IWAS SARS hehe. Kung pwede nga once nabili mo na gusto mo iwasan mo na magbasa ng threads and enjoy what you have purchased.
IMHO, either way you can go wrong...