A buyer choosing an offshore team has four practical options. Here is how they actually compare on the things that determine whether the engagement is repeatable or a one-time gamble.
Reference checks are evidence, not infrastructure. They confirm the last engagement happened. They do not give you a named person to email when this engagement is in trouble, and they do not survive the agency rotating staff or being acquired.
Marketplaces optimize for liquidity, which is the opposite of admission criteria. A vendor with a review can be anyone; a vendor with a Prevouched mark passed a rubric and can lose it. The marketplace also charges the buyer or marks up the engagement. Money flow gets entangled.
An in-house RFP run by a sophisticated buyer is the strongest alternative. And the most expensive in calendar time. Most buyers under $50M revenue do not have the staff to run one well. Prevouched exists to give those buyers the output of an RFP without the months.