Arranger Modules are not in fashion as much as they used to be, and Ketron and Orla are good middle of the road modules, with the Orla tending more towards Organ Sounds.
Going up in price there is the Silverbird from Bohm http://www.bohm-organs.co.uk/ which is more flexible then the Ketron and is also hardware updatable. (You just change the internal hardware when new technology comes along)
Further upmarket is the Wersi EX 1 http://www.wersimusic.com/ex1.html and is the module version of the Ikarus Arranger http://www.harmony-music.co.uk/ikarus.htm with more pictures here http://www.wersi.net/INFOBLATT_Expander.pdf and sound demos here http://www.wersi.net/html/tontrager.html (It can also directly play all Yamaha Styles, and convert styles from other manufactures)
The EX 1 also has the advantage of being totally upgradeable via software and can also use VSTs such as Kontakt 3 http://www.native-instruments.com/index.php?id=kontakt3 B4 http://www.native-instruments.com/index.php?id=b4ii Halion http://www.steinberg.net/155_1.html Real Guitar http://www.musiclab.com/products/realgtr_info.htm and many others.
Another alternative is to use a laptop computer and Midi interface, with software such as OMB (One Man Band) http://www.1manband.nl/omb.htm or LiveStyler http://www.live-styler.de/home/
It’s up to you how much you want to spend, and how sophisticated you want it to be.
The entire above are available in the UK, and the software can be downloaded.
Hope this helps

Bill