Both the Denon 2310 & the Yamaha RX-V1065 have had positive reviews. Between them, the opinion was split with regards to which one is better performance wise, although in WHF group test, the Denon emerged the winner. I agree with other posters. The lowest price I could find online for the Denon 2310 was £629. Who's offering it to you for £580 brand new?
Also, definitely demo both of them yourself as they sound very different to one another. Your listening preferences may be different from the responses you get here.