I have. Tricare Standard, the PPO version. I can see most specialists without a referral, but the costs are higher. I added a tricare supplement insurance which pays the approved cost portion that tricare doesn’t. I like not having to go to a primary provider to get a referral and I like being able to go to my choice of specialists.
I miss my days on Tricare Reserve Select. Low premiums and a $3k cap. By comparison, my “Cadillac” coverage with the federal government has $500 a month premiums and $10k cap which has doubled in the last 8 years.