Random story time but one of the most effective uses of transhumanization in HL2RP I've ever seen was something I experienced on TnB a few years ago.
On TnB at the time, OTA could RP - they were stilted and brisque, but they were more like the Alyx sort of grunts in that they kept a fair bit of their humanity and personality. A few cops happened to strike up a small conversation with one one day and it turned out one of the units had known them - they were a former cop who'd been transhumanized recently.
It wasn't really a 'happy' reunion of course but the talk was good, there were a few laughs on the cops end and there was an acknowledgement that this OTA could recollect that he and this cop had been comrades before. It was a fairly relaxed affair.
At this point one of the CA's comes in and there's some IC drama with the unit the OTA knew, I can't remember what over but it was serious. The CA orders the OTA to beat the shit out of him and where the Cop RP'd stepping back and raising his hands the OTA just steps forward and drops him.
There's no acknowledgement of the former bonds of friendship, no regret or pause. The transhuman beats this cop almost to death before he's told to stop and does so.
That to me I think is something I'd love to see explored more. You might have a conversation with an OTA but they're not human - if they get told to do something they'll do it, no matter of any former bonds or ties.