When it comes to big flies, I'm thinking about pikeflies. Not all pikeflies are big (although the "small" ones are usually quite a lot bigger that most flies). A "small" say 4-inch flashabou pikefly can easily be cast on a 6-wt with the right line. The big ones need more weight - back to that later.
I use shooting heads most of the time - presentation doesn't matter that much, and 90% of my pike fishing is done from either a float tube or my Andersson Speedster pontoon boat. And sitting in either of those, changing a shooting head is fast and easy (although I often have two rods ready).
There are some really fine big fly fly lines on the market, and I enjoy using them - especially on a boat where you have a little more height over the water and often can stand.
I've more or less always fishing 8-wts when pikefishing. Sometimes a little too heavy, sometimes a little too light. Not because of the fish (although it's nice to be able to muscle a pike away from snags), but mainly because of the flies. As I said, many pike flies can be cast on a 6-wt with the right line, but often, using a really big fly lures out the really big pike.
The ones in the PoD are about 30cm long (app. 12 inches) and can be cast on an 8-wt. But put a little wind into the equation, and maybe even a Wiggle Tail on the back, and the 8-wt is a little undergunned.
So - I'm now awaiting Lee to do his magic on a 10-wt Hot Torpedo I ordered. That'll give me the extra line weight I need to more comfortably cast those big flies with tails when it's windy (which it is most of the time). I have two double hand shootingheads reserved for cutting up for this rod. I think I can cut them to 24grams and about 8,5m, and that'll be a good starting point. I've yet to try the HT 10 with shootingheads, so the first tests will be based on what I use for my 8-wts. I'm confident the rod can carry even more if needed, but 24grams is more than enough to carry these flies and I don't want to cast and fish heavier heads that I need to.
Have a great weekend!