Oh I agree, and the iQ10's I've been using for the past 22 months have been sufficient for acting as rear surrounds. For the limited amount of movie watching I've done I've not been unhappy, I just want a consistent quality for all 5 speakers for when I do watch DVD, Blueray and Netflix movies.
As stated I do listen to music in 2.1 stereo, and am blown away by how perfectly these R500's put out the lower frequencies. I think I can set the SVS SB1000 sub at 60-80Hz and be fine.
You may be right about the R100 being good enough for the rear surrounds. That way I could afford to give my son an SVS sub. I left him with the one I bought to "break it in" for me, but he texted me last night to say "someone stole it." I think I know who the thief is.