What's typical of hormones is that either high or low levels cause problems. Therefore I'm not ready to say that leaving LH obliterated by TRT is necessarily preferable to adding some appropriate amount of hCG to the protocol. As you suggest, more research is needed. Personally I wouldn't be too worried about cumulative hCG dosing of up to 500 IU per week. I base this in part on anecdotal reports about side effects—their increasing likelihood could be a proxy for excessive levels.
Are you on exogenous test right now? Do you notice subjective changes in cognition from backfilling the gnrh and LH pathways through using gonadorelin and enclomiphene?
I'm still torn on the benefits of adding HCG low-dose, due to the purported benefits of HCG on brain health through LH receptor signaling.