Boxster S engine mount troubles

[djmunsey]

A few months back I had a local shop replace the engine and tranny mounts, replace the clutch, and do the RMS factory mod on my Boxster S. A couple of weeks ago I started hearing strange noises that I couldn't pin down what they were. Yesterday I removed the engine access cover behind the seats and took a look. What I found was that the engine mount to engine bolts had backed out and the casting on the front of the engine that the bolts pass through was badly cracked in 3 places. All the result of the technician forgetting to tighten and torque the bolts. The cracked piece is the cover for the oil pump and is removable from the block. The shop is going to make good on the job at no charge but they want to weld the oil pump cover and I am not wild about them doing that instead of replacing it with a new part. They said they would stand behind it for as long as I own the car but I still don't feel good about it and I am trying to make up my mind if I should let them weld it or insist on a new or used serviceable part.
Any opinions on this??