The main difference between OMB Arranger play and Live Band play.....OR, why it makes little difference what type of Arranger you play (professionally).
The reason is simple. With Live bands, people come to see the BAND PLAY; with Arranger-based OMB's, people come to see (and hear) the SINGER SING. If the singer is really, really good, it matters little whether the OMB/singer is using a T5 or a PSR3000 or a PA80 or an Audya (no matter how 'Awesome' or whether or not it's been upgraded with AJsonic

), to accompany themselves, assuming the same level of playing ability on each. Don't believe me? See how many OMB/Arranger players do an instrumental set or, in most cases, even ONE instrumental during an entire gig. The exception, of course, being Ian, the lone Arranger player in all of North America who plays all-instrumental Arranger gigs.
This isn't a knock on Arrangers, just a sober look at the the emphasis we place on possibly the wrong part of a OMB performance (and possibly at great cost). Of couse, what I'm saying here only pertains to 'professionals'. Amateurs and home players don't need to justify anything.
We all love players like Marco Parisi (sp) but how many 'Marco's do we have here. But guys like that are MUSICIANS and sound equally impressive on a workstation (or piano, or synth, or organ). What we're wow'ed by is not the arranger but their playing.
From what I've seen and heard here, the NH gigs are not very musically demanding and could be easily accomplished with the most basic and/or prior-generation Arranger KB's. The art seems to be in the 'entertainment' portion of the performances, ala singing and audience participation. That's probably as it should be for that type of venue.
So, Pro's, you may want to think twice before shelling out 5k for that new 'latest/greatest'.
chas