I am aware of the 3db gain formula. However, there is a very noticeable difference when using the 663 and using the 1800. Thus, the 1800 just flat-out sounds much better albeit louder and cleaner. Maybe I just want to use my discount on a better receiver.......LOL!!!!!

Phil
You know it depends!! I mean, you did not do a bias controlled test right? I have enough power reserve in my system but even when watching LOTR movies, at the SPL that I can enjoy without feeling a pain in my ears/brain, I am sure a 663 would have been more than enough. Regardless, I do think that more power is good and you cannot have too much of it but you can say the same about money. So I suggest you first make a list of your must have features. That may lead you to a quicker decision. Since you are already looking for more power, you should stay away from the 2308 CI because it does not have preouts that allow you to add an amplifier should you want more power again.
To me, the following features are a must (minimum):
- 3 or more HDMI 1.1 (but you will get 1.3a anyway)
- Ethernet port, WIFI if it is not easy to hide the cable
- Direct (Straight), Pure Direct modes
- Independent XO settings for front, center, surrounds
- Weighs at least 35 lbs if class AB
- High quality speaker binding posts
- Transformer hums inaudible from a couple of feet away
Features of no use to me:
HQV (Reon) - the BD player that I have in mind will do upconversion well enough anyway so I am not going to pay for the Reon. It would just sit there and produce heat (unless it can be turned off) that helps degrade the other electronic components. This analog to 1080p conversion thing is plain silly, I have SVHS and Hi8 but no matter what you do they are not going to look like even 720p never mind 1080p.
Toroidal transformer - everything being equal, it is preferable but there is nothing wrong with the conventional ones if you don't need the lighter weight, smaller size and the slightly better voltage regulations and efficiency then it is not a show stopper. They are supposed to be quieter too but it does not mean the standard types are noisy, some do and that's why I suggest you make sure you cannot hear the hum from two feet away.
THX certification - why pay for it?
Obviously you will have a different list.
One final point about power and sound quality, I am a firm believer in more power is better but if I am given the choice of a $5000 50WPC (say McIntosh or Luxman) amp or a $1000 200 WPC (say Rotel or NAD) amp for free, I would still take the $5000 50W amp. Of course I mean even if I am not allow to resell the free amp and must keep it for life. Don't ask me why though!