Re: rope & wire halyards vs all rope halyards
If you want to go that big you are probably looking at having to change a lot of equipment first. Few if any of your sheaves will fit line that big, clutches, self tailing winches, fair leads, ect. Will all need to be checked to see if they can handle line that size. Most likely not.
Secondly there is no reason to... A 7/16 dyneema line will have a breaking strength of Almost 22,000lbs.
Smaller line runs easier, and has less friction than oversized lines.
Again, tapered halyards are the way to go. You get the thicker size where you need it for ease of use, high strength, and not much more than cheap polyester stuff.