The KK noise gate is the ORIGINAL Zuul..Fortin copied the Marshall circuit for the Zuul.
Both amps will be killer, can easily do metal with a boost or two. I would vote for the Jubilee as it has a super responsive EQ, very different from any other Marshall. Tons of low end available; much more than the KK. Almost Mesa-like lows. Plus the Jubilee works great with V30s, and every other speaker I've thrown at it. The KK is more classic Marshall in the eq response and digs GBs or 65s/75s best...Jubilee loves all speakers.
Not to take away from the KK as it is a monster as well..I believe the Jubilee is just more versatile with all the different tones you can dial in.