I've narrowed down my upcoming receiver choice to the Yamaha rx-v1400 or v2400. The only difference I'm aware of(except for a few watts/channel) is that the v2400 has an RS-232 port and the v1400 doesn't. Does this feature warrant the extra $$? For those out there who have rs-232 ports on their system, how often have you used it to upgrade the internals? Did it extend the usability of your system because you were able to upgrade the s/w?