I know who I'd rather buy a car from - at least the engine will never wear out!! Prevention is is usually better than cure and you'd only have to search the engine section to find out what can happen with Valeo rads and the damage they caused.
I've recently had a similar dilemma when I replaced the rear air springs on mine, as I only needed one, but it would be madness to pay for the work involved twice (full airmatic, so considerable). On the other hand, I could have saved the cost of the other air spring, and moved the car on. Buyer beware!