Mech + insightful damage not stacking.

[Cyr]

Whoops, you can't do this...14 Arti/6 Rogue doesn't get 6th level spells...

So now I'm back to they should stack...sure, some other Artificer might be able to Deadly Weapons you...but hey, that's what grouping is for...

And if they don't stack, well...I'm not feeling like Artificer is the repeater king anymore...I'd rather just go 2 levels for Insightful Strike and Rune Arms, 6 Rogue for Mechanic...then what? Kensai...? More Rogue?

I think the artificer prestige makes it worthwhile to go six artificer in the build.