Well, both TVs are really in a class of their own regarding the overall picture and sound quality. There are some differences however.
What type of BV7-40 is your dealer offering? There are the first few types, then MKII and the new MKIII. I suspect it's a MKII if the dealer is willing to give you a 25% discount. The MKII is not even near the BV9 so let us assume it is an MKIII. Better ask your dealer about this.
Altough the BV7 and BV9 match in Sharpness, the BV9 has the better picture. Compare them side by side and you will notice that the BV7 is "brighter". The colours are more authentic on the BV9. Not only black but all colours. If you have access to High-Definition via Cable or satellite, the BV9 is a great choice. The slightly smaller panel of the BV7 gives you a better picture with analogue cable.
What kind of setup are you planning for in the future? The BV7 offers a magnificient stereo-type loudspeaker, while the BV9 has a fantastic center speaker which, although fantastic in quality, is mono and is best enjoyed with an additional pair of loudspeakers in the front.
If money is no issue go for the BV9 with BeoMedia1. You can do a lot more with BeoMedia1 then B&O is telling you ;) .
Greetings from Germany
Alex