I've always felt there are two different things...
Playing music, and playing for money.
If you decide to choose a musical path few follow, and styles of music few pay to listen to, you can hardly complain that it brings you little money... If it is musically satisfying, and you are not really trying to make a living, what does it matter if it pays anything at all..?
And if you ARE trying to make money, why pick the most difficult way to do it? Play what the wealthy want to hear, and the money just rolls in. You can always play Jimmy Smith on your own time, for free... (lot easier to get a gig!)
But one thing worries me, chas (and please don't think this is out of disrespect... actually, you sound like one of the more experienced guys here), if you HAVEN'T got out and heard anyone gigging with a modern TOTL arranger, either in a full band situation, or smaller ensembles (down to solos), where do you get the impression that it is not legit?
Is it solely derived from your own usage, or do you have some real world experience to say it can't be done? Perhaps from listening to others do it? If you haven't been out and heard anyone on a good arranger (or anything else, apparently, for quite a while), what makes you so sure the are incapable of the job?
I've got a fully loaded K2500S sitting at my studio, with just about all the libraries they make. But I would NEVER take it out to a 'call' gig in preference to my G70. And, so far, not one single client has ever made a single disparaging remark about it's sound. The player is still 90% of the sound....
Close enough is close enough.
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An arranger is just a tool. What matters is what you build with it..!