Bruce, thanks for the input.
Regarding max SPL, doing some digging I found the max SPL for the various speakers. Other than a few at the bottom most are good enough. Even the lowest ones could work in my small room but good point and worth considering. Movies can have sudden bursty peaks.
DSP5K 108 db SPL max
DSP5KC 108 db SPL max
DSP8K 120 db SPL max
DSP7.2K 118 db SPL max
DSP5.2K 116 db SPL max
DSP 3200 114 db SPL max
DSP 3300 114 db SPL max
DSP750 120 db SPL max
DSP730 115 db SPL max
DSP640.2 117 db SPL max
DSP520.2 114 db SPL max
DSP320.2 106 db SPL max
DSP33 108 db SPL max
DSP420 104 db SPL max
Also, your comment about some of the driver shapes/radiation patterns is a good point. Meridian claims that even their in wall speakers work well with the in room speakers in terms of timbre but that is a relative statement. It may be more true for the 520,640 vs the 320 but i hae no idea as I have never heard them.
I guess that is where I was hoping for some real world expiereince from members on the forums on what has matched well for them in their systems.
Paul