There are probably more 25 and 49 key controllers than 88. There is this thought that if you're a piano player (which few arranger players are) you need 88 keys. Hogwash! Like some of you, I have a very nice acoustic Grand in my living room (which I keep tuned but rarely play) and I'm trying to think of the last time I needed to play the keys at the extreme ends of that piano. As far as needing 88 keys to allow for more 'zones' to play different instruments on one keybed, who DOES that?
The bottom line is, if there was a REAL hue and cry for a 88 key arranger, at least one of the manufacturers would have made one by now. There will always be individuals that want something outside the norm; manufacturers rarely listen to them. Just as the rare pianist who plays an arranger might want 88 keys, the rare organist who plays an arranger might want 61 keys....and oh yeah, an extra manual and foot pedals
. Best bet, if you want an 88 key arranger and a 88 key controller and arranger module (or 2) won't do, do what the guy with the circular piano did; have one custom built.
chas