DET is on point like always. These questions are all so subjective I have a hard time answering any thread these days. Everyone wants a definitive answer, myself included, but like my good man DET stated you have to see how you respond.
I would not go over 1500iu, at that point I feel that you have in a sense reached a saturation dose and going any higher will probably not provide much benefit and like DET stated, hcg cause aromatizing from the lydegs, this is estro that really is not effected by an Aromatase inhibitor (AI).
And as someone above posted about there testosterone replacement therapy (TRT) dose plus hcg and needing .5mg adex eod I believe. For me, 150mg prop ED, I only need .25mg letro 1-2 a week, 1g of long ester test.3 adex 1-2 times a week, and aromisin maybe 6.25-12.5 every few days. So we are all very different.
DET has a lot of knowledge and experience and has written up many basics based on average males for us to start as a guide, but then you adjust as needed from there. Some of the studies I've seen, 25mg a day of aromisin did not crash the estro in normal men, and they were not on gear, yet I can't take close to that dose, maybe I'm turning into a woman and need more estro, lol.
But you are on the right track, 1 you are taking advantage of hcg use, and two you are considering the possibility of sides or increase in estro. I wouldn't get to worried and start increasing doses just yet, go based off previous experience, and if no previous experience, stick with the dose you have been on, and increase by small increments if needed.
DET I use to hate letro, but I'm enjoying using such a small amount. I got really bloated from too much prop (just in face) so I took one dose of letro and I must have pissed 20 times that day, I kept waking up in the middle of the night. Lol. But it worked well