It's not hard at all. For the most part it is set to 40 and started at the end of a play. Unless there is some kind of administrative stoppage (i.e. score, penalty enforcement, change of possession, injury, time out). Then it's 25. We've been experimenting with it in Indiana for the past 2 years and have had almost zero issues. The most common issue we've had is since the R doesn't have to blow his whistle to start the game clock after a first down in bounds, the game clock operator misses it. That seems to be operator specific though because it either happens several times during a game or not at all. But the play clock has rarely been any more of an issue than when it's just 25. We do have visible play clocks in almost every stadium (I've never worked in one that didn't) which I know is not common.
So Brian -
There are many states that do not have visible play clocks.
The idea of going to a 40/25 second "INVISIBLE" clock seems not only foolhardy, but a bit askew!
As such, I would not support this change.
In fairness to you however I agree, with VISIBLE clocks, 40/25 is clearly the way to go.