I will throw my $.02 here and you can make of it as you will.
1) The energy C-100 bookshelves are incredible, i have them as the 2 back speakers in my 7.1 system. They sound great.
2) The C-R-100 surrounds are set as the side ones right now, and they are awesome, at one point during my setup my front speakers were not being fed by multi-channel input but for about 10 minutes i thought they were there because of the reflections caused by the C-R-100's. These speakers are great and work awesome for surrounds.
3)Test out the difference between 4x bookshelves for sides/rear, 4x surrounds for sides/rear, and the possibility of 2x books for rear + 2x surrounds for sides. I have heard that rear speakers are better suited as one directional for 7.1.
4) Finally this is an email from Athena when i was considering matching the Athena LS line with the Energy Surrounds since Athena has no surrounds
"With the side surrounds, the method of transmitting sound bi/di polar is more important than the exact timbre match with others in the series. "
Take that as you may, Energy will get my votes as an excellent choice