An unfortunate fact of the music industry is that bands are now corporations, they exist independently of the members.
I remember once back in the day when I was still working in theater, I was hired to do sound for a show that included the Coasters, Platters, and Drifters. Being a lifelong fan I was excited to talk to them and at dinner I was sitting with one of the groups (I think it was the drifters, this was a few years ago). I knew most of them looked way to young to be the guys who recorded Under the Boardwalk, and during the course of the conversation I was told that the oldest member actually sang with the original members...but that the original members have all been gone for years.
edit: looked it up to make sure I wasn't remember the wrong..according to wikipedia there have been around SIXTY different members of the band.
So if you go see them you're not seeing the guys who sang the singles you're familiar with. You're seeing the company that owns it and their most recent employees (although admittedly, still great singers...you won't get bad show, you just likely won't get the show you probably thought you were seeing).