4 ohm vs 8 ohm taps

I just had my CJ MV75A1 tube amp rebuilt and the tech put on new binding posts and put the 4 ohm taps on them. I always thought 8 ohms was the most common but I dont know much about this subject. Two two sets of speakers I would use with the amp are either my Vandersteen 2CIs or my Klipsch La Scalas which with the new crossovers are 8 ohms . My other amps are all running the 8 ohm taps right now. I could use enlightening on this whole subject. Carl