I would connect the Infinity's to your Yamaha system if you want to test them out.
Of course, Costco takes everything back no questions asked so why not open up both the receiver and the speakers?
You're probably not going to find a tss500 vs energy take 5 comparison anywhere. The Energy is one of the mos popular satellite systems and has several threads on AVSForum. Haven't really seen anything like that about the TSS-500.