I just got a chance to measure mine through the glass today and he's just over 13 inches long at an estimate. Maybe longer, maybe shorter.
This fish has more personality and character than any other fish I have ever owned. It sees me coming, and if I have a white shrimp in my hand, swims to the top and begs for it like a dog. So cool.
Past feeding, the others here are right in regards to the anger and resentment these fish have towards tankmates. I don't know how big your wrasse is, but my fish would probably kill it, even if he wasn't hungry. Size doesn't matter, neither does the dorsal spine. It'd get skewered, and that'd be that. There's just something about these fish, and I for one think they are beautiful. I love how their tails are slightly larger than their cousin's tails, and it seems that if in a good diet, they do get somewhat colorful, with reds, yellows and oranges in the fins, and gill plate area.
Different strokes for different folks. Your wrasse is fun in an eyecandy-ish way, but it doesn't look that neat to me personally, just as armatus look bland to you.