The main drawback to the EVO sprocket, IMHO, is the fact that you are eliminating a very important device which is critical to the health and well being of a marginal flywheel assembly (crankshaft). The purpose of the compensator isn't rider comfort, it is protection for the mechanical bits and pieces. Folks need to understand this before making a decision to eliminate the compensator. As for the IDS eliminating the need for the compensator, I don't think so. One other point for those with new bikes; I wouldn't expect H-D to honor the warranty if you have a subsequent crank, primary, or trans failure after your modification. The EVO folks might try to imply that their part won't cause a problem, but I don't see them stepping up with a definite statement and warranty to protect you.
Just my opinion, but until someone comes out with a smaller sprocket that retains the compensator, the safest approach still involves changing the final drive ratio (trans output sprocket).
Jerry