Pos: I can redo everything with much more skill and already existing roadmap and plans.
Cons: I must redo everything. Not just the comic, but all the supplementals, tools and extras too. Which will be a MAJOR pain in the ass.
But in general, I'd probably manage to catch up to my current story progress within a year instead of, ah, four years. That would be nice. And would give me a more numerous and robust fanbase, probably. Then again - how much far back? To moments before I draw my first page? Or to moments before I'll get the first idea about it? Because for the last it would be a time travel back for one and a half decades, and I'll have much more serious things to worry about than a silly webcomic.