That is the right kind of comparative info to put out they are a good bang for the buck.
And agreed on the HP gain; higher CR is good to widen torque band but not the peak HP. (And the CR bump is really what you can use if you want, not "alleged") That extra flow is worth some real HP.
We are happy with 375-400 HP so either is fine for our type of use and value the higher CR effect on torque improvement.
BTW, if you get the Edelbrocks, and the shop that checks them has a Serdi valve machine, then it is a quick job to just open up the intake ports right below the valve seats as part of the checking, and gain most or all of that flow difference back versus the IMM heads. We spent all of $110 on the checks AND the Serdi work here at a good shop. (But our shop rates seem to be lower than average, so that cost may vary.)