Hi Chuck
Arrangers are designed for the home player, therefore they are designed as easy play, so that you can just press a button and everything is done for you.
In the pro world (Except for basic work) this is the last thing that is required, as it means to customise a sound to your own personal requirements; you first have to remove what the manufacture has added for you. In addition programmable real time controllers are a must, which is something else arrangers lack.
If you are prepared to put a bit of work in, then you will soon start to realise how limited arrangers (Including the T5) are compared to workstations and software instruments.
Fortunately for you, SZ member Bachus is well ahead of you, as he has been using software for years, and also has a T5, so he will no doubt chip in with suitable options. (You can also pm him)
Organ Sounds
For Hammond (Plus some Vox and Farfisa voices) it has to be the
VB3 by GSI, and for Classic, Theatre and Church,
Hauptwerk is the way to go.
For the rest I suggest you look at complete packages like
Garritan ,
Halion Sonic and
Komplete 10 Hope this helps
Bill