A pickleball sponsor offered free balls if we sign a durability quote we haven't tested. How do I push back?

The proposed caption said, "These last longer than any balls our club has tried." The sponsor had offered our US recreational pickleball club ten free balls if we posted the quote with a team photograph. None of us had tried this batch.

Our organiser said it was just promotional wording and would save the club buying supplies. I suggested thanking the sponsor for providing balls, without the comparison. He said the company had asked for a testimonial, not an announcement.

The [FTC's endorsement guidance](https://www.ftc.gov/business-guidance/resources/ftcs-endorsement-guides-what-people-are-asking) says endorsements should reflect accurate experience and opinion, and explains disclosure of connections involving free products. I don't want our names beside a performance claim we can't support.

Would you refuse the proposed quote outright, offer a clearly disclosed statement after we've actually used the balls, or ask the committee to decide before anyone posts? The uncomfortable part is being cast as the player who cost everyone free equipment.