It is rare for me to wrap either butts, or brisket. I like the added texture of the barked - pulled and added in for pork - or just as a crust on loaf bread, when it comes to brisket.
But - I have no problem with wrapping - if I am going to hold and keep warm or transport meats. You will have a softer bark, but no one with complain.
So, there really is only one rule - like Aclarke said - make it the way YOU like it
- and share pictures and recipes with us!