Personally for me it is layers key to success, my first layer is a Jersey than if it is a little colder 40-60 the Gore Phantom is the next layer. If it is super cold 30 to 40 I put on my Arcteryx micro fleece under the Gore Phantom. Haven't had problems with the Gore's waterproofing, although I haven't ridden in any rainstorms. Although I did manage to accidentally stick my arm in the shower and it was dry. I would recommend for precipitation getting a hard-shell no insulation jacket would be your best bet. Also remember that the body loses heat through the groin and the head,if those are properly protected than you will still be cold. I wouldn't suggest one wonder layer because all the esoteric properties don't exist. Such as a hard-shell being water proof doesn't always breath well. The same can be said about some wind proof layers not breathing. And a breathable base like a jersey doesn't block the wind or rain to well. Therefore I would suggest layers not a wonder do all solution

Cheers,