Hi Kingfrog
You are looking for a Workstation with arranger functions, whereas all the boards you mention are arrangers, with some Workstation functions.
Probably the closest you will get for your requirements is as John said the Lionstracs Mediastation, however be prepared to put some work in.
Conversion of styles works best when it is fully integrated into the board, as then the manufacture has full control of the set up; otherwise you will need to use something like EMC Styleworks. (Even the best still require some work after conversion)
Converting Midi to a style will always require some work, so look for instruments that have features dedicated to this, rather then just tacked on the end.
If you want an arranger that you can add 3rd party software VSTs etc, then have a look at the Wersi OAS range, which has the added advantage of playing Yamaha Styles without conversion, and in the process gives them a more live sound.
Personally from what you have said, the Lionstracs Mediastation is still probably the best bet.
Hope this helps

Bill


[This message has been edited by abacus (edited 04-08-2008).]