switching to HPS from what? No they won't get shocked, they'll just get really happy.
People switch from MH or CFL to HPS when they start flowering, there's no stress.
If your worried, throw a drop or 2 of super thrive or go to homedepot or lowes and buy yourself some b1, normally in the lawn section. B1 helps with any sort of shock
I keep clones under CFL and Flower HPS. I never have issues but I do keep the light 2 feet from the tops when I transplant and switch to putting them under HPS just as slipon stated.