mjt - welcome to the forum ..
Re your points ... IMO - broadly speaking - the occasional round which can occuir with a slight deviation from axis as it leaves the gun, is within the short distances envisaged in a combat situation ... still going to do damage - plenty I'd say.
My thinking is .... the sort of tumble which I would anticipate - (when it occurs) - would be in region perhaps of some 5º as an absolute max ... thus, I consider that on impact the HP will still probably try and expand ... if of suitable design .. like Gold Dot - but marginally asymmetrically. Once expansion has initiated, the bullet ''off axis'' element will almost certainly IMO produce a significant yaw .. and thence rapid tumble effect.
Clothing density will, as ever, affect performance but I do think that penetration will be more than adequate and the damage quotient considerable .. possibly even more at a shallower depth than a ''straight and true'' bullet impact.
This really is why I do not treat the possibility of an occasional tumble effect with any great degree of concern ... consider maybe the old days with a 38spl wad cutter ... it delivered an affective hit and probably quickly gained some tumble too - if meeting varying tissue/bone densities .. and yet - results were probably considered well adequate.
So - 6+1 - of the right ammo will for me be just fine ... even if one of those were to yaw a bit. Our aggressor will I am sure not be aware of any great reduction in wounding potential!