Maybe we should come back to Robbie’s initial question, which I allow to repeat in other words: is there a point in gaining where the volume of the penis gets so big that EQ has forcefully to decrease?
A first response can be given directly: I am now 8.7x5.8inches and still can get rock hard erections. So at least I did not reach that point if it is existing.
I guess libido and sexual excitement has more to do with it, as my erections vary over time. But they are, in average, getting better, which I think is result of the PE training. So this should rather speak in favor of higher EQ even for the big gainers.
As to blood: the body is fortunately able to produce the blood quantity it needs. So the penile volume should, at any time, be able to be filled because the body is used to do it several times per night. Just after having a blood transfusion (as donor) there are 500ml missing - but that’s 10%, not more, and it is rebuilt after 1 week for the red blood cells. The blood volume is “repaired” already after a few hours if you drink enough water.
So comes the last ‘line of defense’: body statics. I guess there is a point of volume where the weight of a heavily enlarged penis may reduce erection quality because the ligaments can no longer carry the tension of a rock-hard erection and stretch further downward. This would mean that the erection level (not the quality!) would be lower - it simply bows more towards the ground.
Maybe some of the really huge hung members can drop in their opinion - I am still to small to have the described effects.