I say go for it(!)
The Energy Take Classics ship with 4 satellites, so you should be good to go using those (identical speakers) as the 4 rears to create a 7.1 system. Big tower fronts as right/left too.
I am purchasing the Sony STR-DN1050 receiver but a little confused about which speakers to get with it. Looking into the Energy 5.1 Take Classic or the Pioneer SP-PK52FS. Possible the Energy 5.1 with a pair of the Pioneer front speaker towers. Will this set up work with the Sony STR-DN1050 receiver?