So the Orks in the CA book. Are they on par with how they should be when fighting space marines?

What are your thoughts?

They're probably best fielded as a high magnitude horde, with nobz/warbosses in the mix

As our GM loves orks we've seen quite a few in our current adventure.

The hordes die fairly rapidly to a heavy bolter dev. He throws Nobz at us and we've seen mega armored orks and warbosses now due to the nature of the mission.

None lasted horribly long, but they can be scary in combat.

There isn't a Waaagh! in the area, but there are freebootaz (as there always are). So ship to ship combat is what they excel at, and ramming then boarding. In an enclosed area such as a ship, bolters might not be the best weapons to use. This would more challenging for your Kill-Team, for they would have to engage in melee or use other weapons so flamers and melee in which both SM and Orks excel at.