The issue for me is not origin - I had assumed the origin to be the same, given Tsongkhapa's background, it's changes made in presentation - I'm not even sure if there are
changes, but I do know that there's a pronounced Akshobhya/Vairocana switch in general Gelug presentation.
My question can be put like this:
1. Does this switch (or anything else) cause a difference in Gelug/Kagyu Guhyasamaja presentation?
2. Or, is this switch *because* of the Guhyasamaja presentation itself, which (at least in Arya) centralizes Askhobhya, which is then reflected in Gelug's interpretation of *all* mandala assignments beyond Guhyasamaja?
*I think* I found some evidence in Garland of Mahamudra Practices
that indicates there is no switch insofar as Vajrajapa is concerned.
It's not that I distrust the Gelug sources / presentation, it's that I want to make sure my practice, as limited as that is, is as unconfused as possible, especially since I am wholly reliant on Gelug sources for this, and my lineage is nominally Kagyu.
Right now the only thing I do is vajrajapa, so I would at least like to get that right. Any light shed on these questions, or anything else related to the topic, is much appreciated.