The relationship between DP, director and production designer are the nuts-n-bolts of the film. They have to come together as one. If a link is off, the film could fall into jeopardy, as in pissing off the producers or the gods above and diminishing the rhythm of the crew.
ON hiring a DP, my take is to break it down to your top two or three then take them out for a scene, prep. With this op, you could see how he works and how ALIGNED he is to your creative vision. Ask your self questions: does he start improvising without at least consulting with you, does he get himself out of holes and come out looking nice? is the final look the take?
I once had a DP with a great reel but when it came down to shooting, the guy became thunder. he practically changed the shot list, over-rode my creative vision, and missed 2 crucial shots.
I say when you pick one, have long coffee times, talk about as much as you can and if he doesn't have some kind of track record, test him in a real situation, as mentioned above, that day will save you lost sleep and $$$$.