Not sure of your dosages but AIs are simple and effective even at what most any would consider high dosages. Just my opinion but if merely controlling E2, I don't see the need to complicate. If one wasn't sufficient I'd probably try another long before pairing them up.
Do you even need an AI? Have you gotten any bloodwork recently to see what your estrogen, progesterone, free test, total test, etc? No need in taking an AI if you don’t need one! Fortunately for me I do not need them. I keep ‘em on hand if something pops off, but remember estrogen is your friend in gaining mass! Just have to find that special balance.
About 12-15 years ago there were some 'coaches' who were big into doubling up AI stuff the last 10 days or so to really try and dry out... This was when people moving more into running stuff like test and drol straight through a show instead of the old school dry compound only strategy Yeah, maybe you get some synergy from running an AI with a SERM, but if you are still holding water while on a decent dose of Exem or especially letro, i doubt the issue is estro from only running one AI, lol... person is probably just fat or they are using fake stuff.
The only AI type compound that would really give an effect beyond the others is the one that bombs cortisol and possibly killed Munzer. I'm not going to name it because it is not worth doing. Makes you feel horrible.
I'd imagine it would work well paired at lower and higher doses especially given different mechanisms as you mention. That said, in 99% of the cases it would make more sense for the user to just find one that works and figure out their dosage.
People fuck around with this stuff way too much and get lost in minutia or exotic combos/dosing schedules etc. I'm honestly coming to the conclusion that there's a subset of people that just like to play with peds/drugs and lose site of why they are even using them in the first place. To each their own but makes me scratch my head.
There's no rationale for combining AIs (besides inaccessibility to the preferred drug), but combining an AI (for absolute systemic estrogen concentrations) & a SERM (for modulating the effects of estrogens on a tissue selective basis) makes sense in many cases.