Arena Team with Rex Lead

Who would you recommend I replace with Thrawn? My arena team is Rex (L), CLS, R2, Boba Fett, and Old Ben. Going up against a variety of CLS and Empire teams that include Thrawn, Chaze, Raid Han, R2, Emperor, Vader, I win most fights. But I'd love to use Thrawn once I get him to gear 9 or 10 and will be able to Zeta ebb and flow soon. It's been a tough choice as Rex is great as lead and his cleanse ability helps a lot with Empire/Sith teams. Boba is nice for the ability block and execute especially against Chaze teams. I thought about replacing Rex and using CLS lead as Old Ben and Boba ability blocks would go well with Thrawn's basic. Any suggestions?

https://swgoh.gg/u/blackrider622/collection/