You don't get a killer combo from two products from the same manufacturer, IMO...

BK-7m and a MoXF... that's probably killer.

BK-7m and a Kronos... even MORE killer.

And, you never thought you'd hear me say it, but... BK-7m and an MS?

Yowzah! Killer...

But two Korg's, two Roland's, two Yamaha's... Just not enough variation for me. It's like coffee flavored ice cream over coffee wafers, covered in coffee sauce! You'd better REALLY like coffee