Not a sin. No. But heavy!!!
I brought mine and used it twice ... and Archie used it once in Plymouth for an HDR that may not have come out since he never posted that pic.
So there. And for all that I carried it in The Monster (which was what I soon enough called that heavy, heavy bag of mine) for 12 whole days.
But Conor, amazing as it may be to see you handheld this for so long, you will see that the use of a tripod is in the end essential for nighttime photography, don't you?
Ah, only now am I reading Mentos' comment right: It IS a sin not to take a tripod on holidays? Yes, may be, but to take it is HEAVY. I shall stick to that!!!