I'm positively inclined towards the changes. It adds a bit of strategy and requires adaptability, and since this is a thinking man's fake baseball game, that's a good thing.
How drastic the need to adapt is entirely contingent upon the unanswered question asked by Mike and others: Will INT'L, HS, and COLL scouting remain as they are (determining both the amount of players scouted & the quality of the projections), or will ADV now affect the projections seen for prospects in the international field and amateur draft?
If the former, the change is a minor one and will just impact the decision making process when considering trades. In fact, 0 ADV would not only still be a viable strategy, but may remain the best one.
If the latter, it's a pretty extreme change and will jack ADV up from utterly unnecessary to one of the more major budgeting concerns. You won't be able to trade well, draft effectively, chase INT'Ls, or do much of any team-building activity outside the free agent market w/o it.
So out of 31 pages of jabbering, the answer to that single question would clarify the most.