Jinx,
my guess is that a professional songwriter has a lot of gear to record his songs so, arranger-wise, he would need only a good rhytm section, to lay down the backbone of a song. He will then be able to beef it up with sounds from synths and modules of different brands, depending on his needs. All that said, I think that some of the top arrangers today available can compete in some areas with many dedicated synths, and I think especially of Roland (VA7) and Yamaha (PSR 9000 and 9000 pro), which both have great "bread and butter" sounds, like pads, strings, synth sounds, brass, etc.

BTW, I too think that you have a great website.
Andrea