Sounds like it would have been a great show. I can't say I am a huge Rare Earth fan, per se, but I've just always been taken aback by Rivera's power vocals, especially early. He's just one of those singers that makes you turn and go, "what the..." when he really cuts it loose.
I have to admit, I'm not sure I have a "wheelhouse" so to speak. I'm all over the map within that era, depending upon mood. I can go from Elton John to Zeppelin to LRB to ELO to early Sabbath to disco to Supertramp in one afternoon and genuinely enjoy all of it. Admittedly, a little strange, but it's a fact.