I'll throw in one more comment:

My most successful attempt at an "arranger-based band" was a trio I formed with two singers and myself as the band. That worked just fine (except for dealing with the singer's egos). One time we were hired to play at a wedding and the client insisted that we had to perform as a four-piece band. We explained how unnecessary this was and the added costs but it was no use - four piece or no gig. So we hired a drummer who brought a drumKat midi controller and played percussion parts like congas and latin instrument sounds via midi off of my keyboards. That worked fine too, and I've seen other midi acts now that featured percussionists rather than drummers along with other musos, and yes they used sequences and sounded quite good.

And when I went on a cruise to Mexico last year, I saw LOTS of bands based on arrangers... they were everywhere, on and off the boat.