Is it necessary to plan for either the front height speakers or the rear surrounds? Why not both (and run the speaker wire for both) so you can implement whichever approach makes the most sense in the future? It seems safe to assume the 997 will not easily permit the height front speakers, but in 3 years when the 999 comes out, wouldn't it be nice to be able to easily add the new amps for your 9.1 system?