While there are other red flags in that ad, having a lot of tunings is not that big of a deal. I've been in a band for 8 years that plays very similar music and we go through about six different tunings a night. I play a five-string for all material, but my guitarist tunes in standard 440, drop-d, drop-C#, standard a whole step down, B standard, and drop-a. He has a number of hardtail and Floyd-equipped guitars and can do drop tunings on his Floyd-equipped guitars with a D-tuna. He generally bringa four or five guitars to every gig. Making sets flow well isn't that big of a challenge. When I write setlists, I just start each block of songs with a different tuning on a song that contains a bass or a drum vamp for the intro. That gives my guitarist time to switch out guitars. The truth of the matter is that if you play modern rock covers, your guitarist(s) needs to be able to handle multiple tunings - at least 440, drop-d, and either drop-c or drop-c#. So much modern material is just in such diverse tunings.
However, the fact that they're playing in both E and Eb is not exactly efficient. Most bands choose either to play all standard tuning stuff in 440 or a half-step down. I did some sub work for a band that, with one exception, played all material in the exact key of the recording, including stuff that was tuned down a half of step. However, the guitarist played a 7-string Musicman all night. It did make learning some of the tunes that were heavy on the open E a pain for me though.
