I'm assuming you don't have to shoot traditional equipment right?
Not at all! Even Ted Nugent can do it with a compound. [8D]
Barebow shooting with a compound is very effective. It just takes a little extra practice to keep the eye sharp. A couple of years back, I won compound class at a small local 3D shoot. I was shooting an old Hoyt, fingers and barebow, against about a dozen others shooting all the latest, greatest stuff. A couple of 'em were set up forunlimitedclass but they obviously weren't very good at it since they came in 2nd and 3rd.
As to how long it took me to get proficient... I really can't say. I started shooting a bow when I was a little kid and never 'got' proficient. I just kindagrew into it. I've seen some guys pick up on it and start shooting very well out to 20 yards within a couple of weeks. And I've seen some that simply didn't have it and never got proficient at any distance without sights.
But you're right that someone who can shoot accurately without sights has a good many advantages in the woods.