I would buy an XD-9 or SD-1 if it has the following:

-Similar priced to Yamaha PSR2100 or KORG PA80 respectively.
-At least as much functionalities and weight as PSR2100 or Tyros respectively. You can drop the color screen.
-Internal speakers as loud or better than above kybds. Some days, I just want to plug it in and play without worrying about amps, etc.
-Better or equal sounds in all major categories than above. All you need is some killer sounds in those major categories and label it like YAMAHA does. Sweet sax, Live piano, etc.

Bottom line is you need to beat Yamaha and Korg. Even a slight edge will do it. The fact that the marketing is poor will sway a lot of users just because you guys are SLIGHTLY better and cheaper. You don't have to be MUCH better, just sLIGHTLY.

An example to give SLIGHT advantage:
-Match the specs of PSR2100 but add longer 76 keys. Like CASIO WK series did but their sounds are awful. And if your prices are similar to PSR2100, I WILL JUMP BOAT AND GET THE KETRON instead.

OR just match PSR2100 and provide a louder speaker (like CASIO WK series).

OR just create a lowend keybd like CASIO WK (below $500) series and put expansion slots to add stuff to make it match the high end arrangers.

CASIO WK series is only like $200-300 for a 76 keys board. If you just replace that internally with a PSR2100 keyboard, I will dump the PSR and get that one instead in a heartbeat !!!

I REALLY don't think it's that hard. The product will sell itself. At least in this forum. I will recommend it to all my friends.