Been doing the libero serving here in Michigan this season without any problems. It basically means the libero can be in the floor all the time - except for 1/2 a rotation when they need to sit out.
The hardest part to get used to is when the libero heads from the RB to the LB to serve. The two players that exchange in the libero zone are neither liberos!
If makes you cringe the first time you see it, but you get used to it quickly. You also need an assistant score-keeper (libero tracker) that knows what they are doing.