The Cinema 30, in my opinion, is the best overall AVR/AVP at the moment but just in case you may not realize, the AVR-X6800H ADTG mentioned, will do exactly/or at least virtually the same. So, between the two, if the preferred look, 2 year longer warranty = $1,000 more then go for it! If you want to spend the $1,000 saved by going with the Denon, and spend it on a subwoofer upgrade, then you will most likely end up with audibly better overall sound quality, but then every time you
look at the Denon you might wish you had gotten the Marantz.
The Cinema 40 is cheaper, but if you are in the USA or Canada, you have to really like the Marantz look and dislike the Denon's, otherwise the often on sale AVR-X3800H is the best value, same sound quality, almost same features, for roughly half the price.
Feature wise for sure, but don't expect audibly better sound quality unless you use RC/EQ. The Onkyo you have is well beyond the point of diminishing return.
If you do use RC/EQ, in this case Audyssey, or Dirac Live, especially if you are prepared to spend some time do some post calibration tweak, then you will get better sound quality with the AVRs you are considering, or if you want to stay with Onkyo, the RZ30 (9 channels processing only), and their higher models will do too.
Last point, a better subwoofer, such as SVS's, even if you can only place 1 in that room, will make a good difference.