Seems straightforward if it's accurate: Any given amount spent on ADV will be more accurate than the same amount in HS. So with high ADV, your projections will be more accurate after the player is draft than they were before. $20M in HS/COL/INT is not going to be as accurate as it was in the past.
As Mike noted, it will only make a difference if you trade young players. Otherwise, you're still going to want to maximize development of your top signings and picks, and will soon enough know where they will end up. If you have 16 HS and 0 ADV, you'll assume your top 3-5 picks in the draft are worth putting development effort into even when their ADV-based projections are horrible. If you can't stand seeing your 18yo SS's range drop from 85 under 16M HS to 45 under 0 ADV, then yeah, you'll need to bump up ADV. If you can ignore the worthless rating and stick the guy in HiA at SS this season and put him in AA next to see where his range will really end up, there's no reason to start spending on ADV.
Assuming that ADV would have to get up to 14M+ to be accurate enough to rely upon, I'd rather spend that money beefing up coaching so I can propely develop three levels of hitters instead of the two I do now, and boost HS or COL by a few million. Same result, $8-14M/year cheaper.