Re: What if they'd kept T'Rul?
With or without the anti-proton beam, I don't think the concern about the Federation using ONE cloaking device against them. Their real concern would be Starfleet engineers studying and possibly reverse engineering it.
indeed, it seems like an oversight for the writers not to address what would seem to be a huge tactical/security concern for the romulans.
"Thank you.. for the drinks."