I also scout within my scheme, and I did pretty good last time with 3 SuperStar dev players and 2 other decent players. One was a bust and 2 were late rounders that probably won't end up being much. (I had 8 picks)
Considering the amount of scouting XP you get, and how how the draft board looks after doing so, I think that is what they designed the game to do (you end up with even distribution of players through all rounds on your draft board).
Only exception is that I do all 3-4 defenses because I run ZB 3-4 (I am Steelers) and there aren't many of those guys to draft. If you are within any 3-4 you only take a 10 point confidence hit, the guys I picked in other 3-4s came in at 40 confidence. (Eventually I will set my scheme between "attacking", "base", and "ZB" depending on what players I have, the one that benefits my team the most I will select).
I'm pretty sure you get a slight XP boost when you hit your weekly goals when the player fits your team scheme, plus you don't take the confidence hit that some rookies get if they don't fit your scheme.
The downside being that you are limiting yourself to a smaller player pool, and you may leave yourself a bit light in what you can choose from in certain positions depending on your scheme. Like you may only see 1 or 2 LT that have balanced offense in the whole draft (for example).
I don't really put a premium on player type either, while it gives you an idea of the player strengths, the only thing that matters are the attributes for YOUR set up. If a player is "run stopper" CB for example, he could still have all A's in all coverage skills (in fact this happened with me and I got a stud CB who covers like a corner and hits like a safety) and be the best fit for your team even if your set up in your scheme to have "man to man" corners.
Once I get the double scouting points and have more points, I may tinker with a sort of hybrid system. Where at the top of the draft, when scouting players you are hoping to plug in right away and start, I will do within the scheme. They will come in with good confidence levels and will get the small dev bonus.
But I will possibly expand some of the late rounders to other schemes, it may give you a better chance to find a late round gem with more possibilities. Plus if you are just drafting for depth and don't plan on finding a late round starter necessarily, the confidence shouldn't be too important because eventually you can build that up when you need him to play a more prominent role. He wouldn't need high confidence right away like a higher round pick.
But I do like the idea of drafting in scheme overall it just feels a bit more realistic and does actually have some benefits with the confidence and slight XP boosts.