Hopefully Laguna II Owner may pop over and give some opinion on this Stu.
One thing you have to remember is that a lot of people posting on forums only do so to talk about problems, this can give you a paranoid view of what's going on.
I recently bought a Porsche 996. I was very nearly put off because when you read Porsche forums they would have you believe that every early 996 blows it's engine and ends up costing £12k to replace it.
The truth is that quite a number did have a problem because of a manufacturing problem where by the block was too porous and on 'some' the water and
mixed causing catastrophic failure.
I still bought one because I've always wanted a 911 and couldn't afford a new one, but I was careful which one I bought. Ultimately I may end up losing the engine but I don't let it put me off enjoying the car.
I'm not saying there isn't a problem with the Laguna's MK2 engine, it's probably been blown out of all proportion though.
What year's your car? Is it under any warranty?