You'll need to hear for yourself, only you can decide if they sound good when you hear them together.
As to the two speakers question, I'd been looking at the 609 a few months ago before I heard about the TX-8050 and the reviews were generally positive. The other thing is that this is one of the cheapest ways that you can go about bi-amping your speakers, so you can use four of the Onkyo's amps to drive the V4s.
The 609 also gives you Spotify functionality, and because it's networked, much like the 8050, then you get firmware updates, new product or new functionality and a whole bunch of stuff an integrated won't come near touching.
They'll work fine together. The Onkyo isn't bright, it's just more lively than more laid back receivers. In comparison to a laid back receiver it might be perceived as bright, but in isolation it'll sound better balanced.
Good alternatives would be the Monitor Audio BR5AV package and the Acoustic Energy Neo V2 package, which might cost a little more, but might be preferable if you don't want to worry about your system sounding too warm.