Yeah, mine came out OG 1.063 with a 5.9ABV. So yeah jack it up.
I think the 1084 would be just fine. Although these Christmas ales are considered malty profiles and the 1084 is described as a "Full bodied, dry clean flavor", I've used the 1084 in many stouts, Irish reds and some porters even. I would go with the 1084 if you have it on hand and healthy.