I have always used the 500 round number myself. That means zero malfunctions with no tinkering to get it there. Straight outta the box.
I suppose if by "tinkering" you mean screwing around with no real knowledge of what is causing the problem and what will fix it, that's a good policy.
I'm with ya, Blue. Except, I also want to see at least 200 continuous rounds of perfect function - no excuses.