Not sure if profits have changed much, but I don't think so. Problem I've always had with rares is the limited supply. IIRC, even after waiting until the supply is replenished, there comes a point when they won't have any more for you due to the number of them already in your cargo hold. There seems to now be a hard limit of how many of each kind you can have at one time. Someone can correct me if I'm wrong. This has been my experience lately, admittedly only doing this once or twice over the past two patches (2.3 & 2.4) to unlock a couple RNGineers.