I've got 2.
I've got one in my 120 which I've had for about a year or so. It came in to the store with a few spots, I put it in my reef system (coral sale display) to let the cleaner shrimps do their thing... which they did. While he was convalescing, I started hand feeding him and decided he was mine

The tang police would have a serious anurysm about my 120.. I've got him in with 2 small regals... The regals were traded in from a 75 that the owner was breaking down, they have been together for about 4 years in her care and have been with me for almost 2 years now. They have not grown, and I suspect they may have stunted one another in those 6 years but appear healthy and happy and all 3 tangs fare very well and anyone who sees my tank on a daily basis will attest to that.
My other vlamingii is a relatively new aquisition. He's a fair size, probably 9" from nose to tail. He was given to us by a customer who is moving and was relocating his 60 hex... we are tanking his stuff while he's moving, and yes this huge fish came out of a 60 hex. Guy had him for about 2 years, bought him someplace just before I opened my shop and when he became my customer I advised him that the fish would outgrow his home fast... he's shown no signs of stunting or stress. We've had him about a month now, he's living large in our 1000 gallon and is one of the 3 largest fish in the tank, the other 2 being a large red volitan and a large panther grouper. We also have a large regal, large purple and large yellow tang in that tank, along with a stars and stripes puffer and a school of six Monodactylys argentus (brackish fish, previously kept in a reef for 6 years).
Vlamingii are great tangs... lots of personality, very intelligent and in my experience, easy to keep. I've transitioned a few from small tanks to larger homes for people as they outgrew their tanks, luckily with our large tank and a customer with a 460, and another with a 1200 it's not too hard to find homes for these guys if they live to get large.
I wouldn't recommend one to somebody without either a large tank, or an exit plan, but as long as those criteria are met, they are excellent candidates.
HTH
Jenn