The only "problem" I've had with handsfree is when the management has the card in her bag, and gets out the car to go shopping and I go to park it .... problem, when you stop the car ....
On the Laguna, if the only working card leaves the car and the engine is still running, you get a beeping alarm from the dash and a red warning icon telling you that it can't sense the card. I've also had it happen while driving when the card's battery has been low.
I find a bigger worry with the handsfree card is that it can drop out of your pocket and remain in the car. (Or, more commonly, you park up somewhere briefly, and the wife decides to leave her handbag in the car, with her card still in it.) You get the beeps until the card leaves the car, but you get so used to those that you soon stop noticing them. On top of that, I've known the car fail to auto-lock when the card's gone out of range on a few occasions now. On one occasion, I know I'd accidentally pressed the unlock button, so it's possible that's what happened on the others too.
So every time I park the car now, I have to listen for the beep and/or look out for the hazards flashing when I walk away. Which is fine unless you happen to be walking away from the car across a noisy, busy car park