I can assure you, despite Roland themselves not knowing how to pick and tune the best voices for styles, you CAN get some scarily good electric guitars out of the BK series. Their amp simulators have improved drastically since the G/E series. Check out my two BK-7m/KX-5 keytar demos.

And, although I give the G70 GrandX a slight nod, the pianos in the BK-7 still shine. Once again, I believe that it boils down to the controller... It's hard to modulate your playing strength on an action as light as the BK5/9. Mind you, they are still a bit stiffer than the PSR series. If you want to get the most dynamics out of a keyboard, setting the touch strength to it's minimum (the most force needed to get fff) is usually the best bet, but most arrangers set middle strength as default, and most early demonstrators tend to not fiddle with the factory defaults.

Saxes are still a toss up for me. The BEST SA2 demos make the Yamaha's saxes sound wonderful, but again, it's rare to find a user demo that comes even close. Roland is just in its infancy with SA style voices, and overall, I'd give them a slight nod. But it is still 99% the player that is going to make the difference. In the hands of a good horn player emulator, I think you would find the Roland adequate, at least.

Again, as I still class the BK9 as a MOTL arranger, not the 'flagship' that comparison with a T4 or PA3x would expect, it has much that other MOTL offerings don't have. 76 notes, key triggered audio loops (little buzz so far about this quite handy feature), a Chord Sequencer of some sort, ultra light weight, etc..

Roland at least can't be accused of having a 'me too' arranger here!