Last year I was asked to move back to U for one game. We tried moving the U into the backfield on a 5 man crew.
In my opinion this is a bad mechanic in a 5 man crew. You lose all contact with players, no coverage on the LOS for pass plays, yes wings may hold but when they read pass they slide downfield, the game is not so fast that a high school U can't keep himself out of harms way, for most of his career. My biggest problem was not having that interaction with the Mike LB and Center, I used to know them by their first name and talk to them most every play. If I was having a problem with someone they took care of it.
Not in 5 man, 7 man when wings hold maybe but I would still miss that contact.