Well, a module will of course require a careful placement otherwise, like Scott wrote, it will be difficult to quickly access all its buttons (with an arranger you have to be fast to press the right button, or the result will be disappointing, especially if you perform in public). On the other hand, if you already have a good keyboard and are satisfied with it, a module is a sensible choice. I think that right now the only ones worth a try are the Ketrons (X4 or the new XD9), but maybe I am wrong. I have tried the X4 (thanks to Paul Curzan ) and was satisfied with it. By the way, both Paul and Eric are very soon going to try the XD9 at George Kaye's store, so maybe they will be able to give us their opinion too.
Andrea