I just re-bedded my mast step and everything with butyl tape, (first "off season" with new to me 1978 C27), worked great!
I consider butyl better all around, but particularly, in high stress areas, (I.E. where there might be a chance of movement or flex), it's self healing!
Anyway as far as cold temperatures goes, I just tighten the fasteners a little at a time, wait/do something else, tighten some more, wait/do something else, (all the while trimming the excess so I could see how far it has to go). I do this until the item is seated all the way. It is a little tedious but I can see the butyl squeezing out of every possable leak spot and I know "I'll never have to do it again"!
In short, I love the stuff. And it doesn't hurt that I get it from work free.
Happy sailing,
Joel H.