Most of the conversion happens in the first 15 minutes... If you are only a few degrees off and can adjust the temperature quickly, I don't think it would matter much...
Without calculating/adjusting the strike temp each time, it could end up being quite a bit off if you change variables in the grain bill/grain temps/mash thickness, etc..
Personally, I would calculate the mash strike water temperate and set the controller to that each time... Then adjust the controller to the desired mash temp when you are ready to recirculate (so it only has to maintain with very heating required post strike)...