I know you specifically requested *not* the GNSMS01, but it's an *excellent* 2.1 system. I have it setup in the store side by side with the TRSMS05 on the same keyboard, and at one point the I had the Korg PAAS on a PA4x.
The GNSMS01 is miles ahead in clarity (it's even ahead of most small PA's and studio monitors). If you haven't A/B'd them, you really should, although a pair of MR5's (Mackie now on the 4th gen MR524) was the closest I could get under $400. And still not as clear as the <$300 GNSMS01.
A pair of Yamaha HS8's is even closer, but while as clear as the GNS, not as thick on the low end. And costs over $900. And yes, I'd agree, the JBL's would be close enough! (but almost $500 cdn). Same thickness and similar low end, but very close to the GNS's clarity.
If you're basing this on how 'blurry' the previous Tyros speakers are, go to a local dealer who has both and A/B yourself. The Tyros speakers are *significantly* inferior.
Every Korg PA4x/3x customer who's been in asked if it was possible to purchase a GNSMS01 for their Korg. Alas, unless you know how to re-wire the custom 8 pin connector, it only works on Genos. :/