Is there a study on the added rebounds for each pop RB per position, compared to the added salary of said pop? (I assume that is where you were going with your question). Because even though the study you talk about shows rebounding has more effect closer to the basket, it's not yet representative because you need to compare how many rebounds 1 extra pop on a big with ~16 Reb gives you, versus how many it gives a guard with ~4 Reb, and then set it off against the added salary. Then you can compare wether it's worth to add rebounding on your guards or your bigs.
That's pretty tough to get correct data on I think, but I find it hard to draw conclusions (either way) on incomplete studies.
I toyed around a bit with Buzzer-manager's salary calculator to show the added salary per pop in a few different situations, to determine how much rebounds that pop should add. I compared 4 different guards and 4 different centers, and checked how much salary 1 pop RB added. The players I used are:
16 Guard: 16 in all guard skills, 4 in all secondaries besides RB
14 Guard: 14 in all guard skills, 4 in all secondaries besides RB
16 Center: 16 in IS/ID, 7 in SB, 4 in all secondaries besides RB
14 Center: 14 in IS/ID, 7 in SB, 4 in all secondaries besides RB
and then different levels in rebounding (1 and 4 for guards, 12/14/16 for Center)
16 Guard
1->2 = 3.7k
4->5 = 4.1k
14 guard
1->2 = 1.7k
4->5 = 1.9k
16(7) Center
14->15 = 9.9k
16->17 = 12.5k
14(7) center
14->15 = 6.2k
12->13 = 4.9k
So if you add 1 pop on a 16-16-16-7 Center he should grab 3 times as many extra rebounds as if you would add 1 pop on an all-16 guard with 4 rebounding, because that 1 pop adds 3 times as much salary is it would on the guard.