Hi Bob
You are looking at quite a large number of cars many with different faults, they don't all get all the faults - well mine have'nt so far

I have found the 2.1s generally to be very reliable, after I had fitted a head gasket to the green one and done one or two electrical jobs it rewarded me with over 70,000 virtually trouble free miles, until the wife crashed it.
When you buy them they usually need quite a bit of work, but once you have done it all, as I said have found them reliable, certainly more so than modern diesels which seem to cost £1000 every time they go wrong and do so quite frequently. I have been running them for about 13 years now, and apart from all the electrical problems on the early ones I can't say by any means that they have been unreliable.
They will obviously need some attention sometimes, I've had a few hydraulic pipes go, but if you can do it yourself it certainly isn't expensive, the 2.1 engines and manual gearboxes seem to last forever, certainly 300,000 miles. If you compare what it costs to run your XM compared with a modern car, I think you will find they are a bargain.
Peter
'96 'N' 2.1 td VSX manual estate White RP6695. Sadly gone
2008 C5 2.0. Hdi Estate, Red
2008 C5 2.0. Hdi Estate Silver
Located in Charmouth, Dorset