Here's why many owners, including me, go to 0 Advanced: First, progression patterns are relatively predictable. The game simply doesn't appear to have the odd player who develops say, twice as much as other players, with the exception of DiTRs (who you can see). Second, the fuzziness of projections exists to a degree that we feel already obscures the value of a player. Say you're trading for a player you see as projecting to 80 Power, he could actually end up at 70 Power anyway, which would be a significant difference in your valuation of him. Higher Advanced scouting doesn't conclusively solve this.
With 0 Advanced, I make deals based on two things: Knowing the trading patterns of the league I'm in, and knowing the tendencies of the individual owners. For instance, in one of my leagues the owners are ultra-conservative. Most of them almost never trade blue chip prospects. So if one of those guys is offering up a late first round, or second round prospect, I'm more likely to think the player is actually a fringe major leaguer or Rule 5 type player. In my other league, owners are more aggressive and more actual prospects get moved. The trades are more genuine, I have more confidence in the deals I see in that league.
As for knowing the tendencies of the individual owners, you can check the league history and see the trading patterns of individual owners. For instance, you can find the guys who always trade overpriced veterans for other teams' real prospects, and stay away from them.
Those two observations of the league itself give me an idea of whether to trust a prospect's draft status or IFA value. Because of my systematic distrust of projections on the player's card, I'm not concerned about the actual values they show. I just evaluate whether the player looks good enough to make the trade worthwhile, or a bust.