5.1 to 7.1 System setup

Hello all,

I am considering going from a 5.1 (now) to a 7.1 setup in my HT. I have the speakers already mounted and cables run... just need a new amp. The problem is I stil haven't 'dialed in' my system as it is now, and I'm a little concerned of adding more pain, so to speak. My questions would be:

1. Is what mode the 970 uses source dependant? That is, does it 'know' to switch from DD to PLIIx or DD EX? I have trouble with the unit not staying on the mode I've selected (in the source setup) when switching DVD's, and I can't seem to set it up for just DD.

2. Should the rear (SLR and SRR) speakers be as full range as possible? Right now I'm using 'small' speakers for surrounds.

Thanks for any comment/reply, everyone here seems to be very knowledgeable.

System:
970 pre/pro
Adacom 5 channel amp (?)
Mirage M-3 L/R
Mirage CLR (?) center
Mirage Dipole surrounds
TWO Outlaw LFM-1 Plus Subs
Mitsu HC-5000 on 103" Screen

The 970 offers surround mode memory that is input-specific (it should remember that you use stereo with PCM sources on the CD input and PLIIx-Movie with PCM sources on Video1, for example).

The surround rear speakers can be small satellites - they don't need any more low frequency range than the side surounds.

Thanks for the reply... must be the user. I'll try more tinkering with the 970 and see