Sorry, guys, but here I go again..!
Sadly, the thing about arranger play, and ESPECIALLY arranger play from those that learned to play on an arranger, is the fact that it can sound pretty good, even when you are awful! I can't count the number of truly appalling solos trotted out sometimes by their proud creators at different sites, and if you ask these folks if they can play, they'll say 'sure I can... listen to this'.
Trouble is, stop the arranger and listen to what is actually played, not sequenced, and it's pretty grim. The pre-canned Intro gets you all worked up, then they start playing... ouch! The arranger is the ultimate self-deception tool. Surround a ghastly sax emulation with a pillow of nice bigband styles, and all of a sudden you've got someone who thinks they deserve to be onstage. And, if their price is right, that's where they'll end up!
But if that arranger ever crashes...
But, in the hands of those that can already blow by themselves adequately, or experienced full band players, they can be amazing, but the pitfall so many fall into is using more mechanical stuff than they HAVE to. I try to treat mine like a rhythm section... Bass, drums, guitar (if I haven't got one), and that's it. So how do you get the piano AND the horns AND the strings, and all the other parts, you ask...? Same way you get them if you were in a four piece. You PLAY them ALL. Live. Old school. You don't have a left and right hands, you have two right hands!
Velocity splits, layers, expression pedals... all of these can be used to squeeze more sounds out of your playing than you could ever imagine. But you are unlikely to try it (and hence develop those techniques) if your arranger already does it for you. 'But why SHOULD I learn how to do this, if my arranger already does it so well?', you ask... Well, ask yourself this - what would you do if a great band in your area offered you the position? Good money, GREAT players to play with, music you enjoy. Could you actually pull off live what they have heard you do on an arranger?
If NOT... Time to shed!
Some of you have commented about how much better you sound since you left live playing, and moved to arrangers. I'm sorry, but the only thing that tells us is how poor that band you were in must have been! The thought of a guitarist playing EXACTLY the same two or four bar groove for an entire section of a song (or the entire song!) gives me the willies! Ditto the drummer, and don't get me started about the bassist! That's the one area an arranger doesn't even come close... A real bass player moves TOWARDS the next chord. An arranger bass moves away from THIS one. Totally different approach.
If you THINK you are making music with an arranger, turn it off and play live. Find out for yourself just exactly how much you are relying on the ACC. Then perhaps you can take a more realistic view of whether the arranger is helping, or hurting you at your goal of being a better musician.
As a learning and teaching tool, I LOVE arrangers. I DON'T agree with chas here. If you treat them as a VERY fancy James Aebersold exercise regimen, then they can instill great timing and adventurous solo habits LONG before you would be good enough to be invited to blow with a rhythm section that good. But use them as a reason to NOT learn multi-keyboard techniques and rhythm section play (you are VERY unlikely to get a position as keyboard SOLOIST, most songs only have 16 bars of soloing, tops!), and you are condemning yourself to ALWAYS having to play with them.
This isn't music, this is the FACSIMILE of music. It sounds like music, but it's a recording. That's all arrangers are. Small loops of canned music that follow your chords. No better than an SMF, except there, there don't have to be ANY loops..!
Arrangers are a great way for an experienced player to maximize his profits (and the club's that hires him), but it takes GREAT care to not let yourself get carried away by how good it sounds. And for the beginner or intermediate player, still learning, once again, it's a great tool only as long as it remains a small PART of your entire learning experience...
Technology changes, and at a rapid clip, these days. Invest your learning process solely to arranger play, and you run the risk of being out in the cold when other techniques become prevalent. But learn to do it ALL yourself, and you will be able to adapt yourself to any future technology MUCH faster...