It really depends upon the damage and the required repair.. Personally I would not run a crank that had a crack repair, however if it just had a hurt rod journal, they can grind the journal down past damage and any coating then under water ark weld the journal and grind back to standard. If this is done properly, you will have a hard time even finding the repair. If you cryo the crank after a repair this will eliminate any instability in the weld patch. I would preffer to buy the crank hurt so I knew what was wrong before the repair.
Regards
Rob