Sounds like the KRKs are real nice, but I haven't heard them yet.
What I like about the Yorkville's in particular is the unusually good bass response compared to other 6.5" speakers, yet they're not bass-heavy. One thing for monitor hunters to keep in mind is that if they get a speaker that everything sounds good on, their mixes will sound like shit on everything else.
In many respects the Yorkville's remind me of the Yamaha NS-10s, which were terribly misunderstood, but were/are absolute gold in the hands of the engineer who figured it out.
Though bright, the high end of the Yorkville's is not hash and fatiguing like the NS-10s.
The bottom line is that if there's too much woof, woof, and pow, pow in the monitors some will have a tendency to back those frequencies down in the mix so they won't be overwhelming. That can translate into wimp, wimp on the end-users system. Similarly, if the monitor's high end is not bright enough you will find yourself increasing those frequencies, resulting in mixes that fatigue the listener.
The uninitiated should understand that what is good for recreational listening can be really bad for mixing.
Therein lies the secret of monitors like the Yamaha NS-10s and the Yorkville YSM1s.
I don't mean to criticize the KRKs because I'm not familiar with them, but rather to elaborate on the benefits of the Yorkville's.