I have been running my buderus for about a year now with no problems. I will let you know what it looks like after we do service some time this summer. I did see one at the supply house that was all messed up but my guess would be it was replaced under warranty and thats why it was there.
I think in europe all anyone buys is condensing boilers due to thier energy policies that actually work. Best I can tell they have a good track record over there.
If you want the most cost savings make sure the person who sets it up takes the time to read the manual and knows a little somthing about temperature set points and installing out door resets. Baseboard (especially copper tube) is not an idea heat medium for getting the boiler to be run in condensing (highest efficiency) mode. I can get mine to run in condensing mode about 75-80% of the time which has lead to huge cost savings over oil.
I will have paid for the system and be about $3500 ahead by the end of next winter, so for me anyhow the cost savings were huge