6-line wrasse:
If it's a smaller tank with only 2--5 fish, don't do it. My tank is 30g.
If the 6-line will be one of the larger fish in the tank, don't do it.
If the other fish in the tank are very peaceful and rarely aggressive, don't do it.
If the tank is larger (75g+) and you will have some larger fish in the tank, try it.
If those other fish in the tank can take care of themselves, try it.
Everyone told me the 6-line was a great fish for my tank because my tank is small. Only 30g. I wanted fish that would remain rather small so that I didn't overload the tank. Most 6-lines will not even reach 3" in captivity. Usually, they max out at about 2--2.5" Seamed like the perfect fit. They are supposed to be peaceful fish.
It wasn't until mine turned into an A-hole that I did a lot more reading on them. I found out that they do become bullies in smaller tanks where they are the most aggressive fish. My goby and my clown are both very peaceful fish. That left the door wide open for the 6-line to turn into the bully, and he did just that.
In a 75g tank with some angels, tangs or a school of chromis --no problem. They all get bigger than the wrasse and they are all quite capable of fending off any aggression from the wrasse. Probably kick his butt and that would be the end of it.
Hope this helps.
I'm surprised that a lot of you wouldn't want the reef ready tanks. I hate having crap hanging on the back of my tank. The idea of using an overflowbox on my next tank doesn't appeal to me at all. Crap hanging up and over the back glass looks silly to me. But, I've never had a reef ready tank either. It sounds like they don't really drill the holes big enough. Maybe you could order it reef ready with custom holes drilled? Or order it with the overflows and drill the holes yourself?