Cmon guys, lets try and keep this in perspective.
If you have no noise, keep changing the oil regularly.
Keep an ear out for the noise on start up, but don't get paranoid about it. The chain won't just snap, you should get a lot of rattling for some time first.
When you get a rattle, get it checked out at Vauxhall. Then punt about for a better price eleswhere if they wont sort it at a reduced cost.
Look at it this way, if you have a rubber belt it won't rattle it will just snap with no warning and you is fooked. At least with the chain you get a chance to replace it once it starts to rattle before it snaps, saving loads.
If we are the z22se forum then we need to be confident in the engine. This means that we don't panic and start writing the engine off cos of the rattly chain. It is easily sorted.
We could end up shooting ourselves in the foot, cos no one will want a 2.2 if they think it will blow up on the motorway.
Remember the old Triumph Stag engine ?????????