There is also a huge difference in price between the RTIs and LSis. Also, the LSi's need much more power to drive, so that will clost you hundreds more for an amp. You are comparing apples to oranges.
I agree, I could have done better for my money than the RTI 12's. But at $899 or whatever Polk is selling these for now, they blow all those away you listed. The 12's are in a different leaage than the 8's but at the same price now. How is that not a great deal??? And another thing, the RTI series are inefficient, requiring more power so you may have heard them with a low powered receiver. Not a fair audition IMO
Yamaha's brightness does not show up in the specs. It's how they sound. You can believe me or not. I have tried 4 different Yamaha players and they were all bright. Maybe using less detailed speakers as you stated would even out the brightness, but Polk speakers, being bright and detailed as they are, are an awful match with Yamaha.
I don't really care if you believe me or not. Go waste your money. I have spent a year experimenting and I am helping people with my experiences.
JC