I've had two separate people send me requests to fix cracks on frames with holes like this, which biases my opinion. Both instances the solution would have been to replace the top tube, both times the frame wasn't worth the expense to the owners.

Perhaps the fact that people with problem frames tend to seek me out biases my perception of the magnitude of the problem. Anecdotal evidence is always hard to account for. We don't have any real statistical evidence.

Bondo won't stop a crack from propagating, but it will stop water and sweat intrusion. That's an area that gets a heavy dose of dripping sweat, so cleaning and filling or covering it makes sense to me as a minimum.

If someone gave me that frame, it was my size, and I wanted to ride it, I'd fill it in the method I posted, but my labor's free to me. I filled several cable guide holes in [MENTION=168558]Drillium Dude[/MENTION]'s Casati for aesthetic reasons, and it was nowhere near $1000. Most of my repair jobs get either paint patched (glossy black works out pretty well, for example) or powder coated (~$150 at my local place).

Maybe the best compromise is to fill it with JB weld, carefully sand it down trying to avoid damaging the surrounding paint, then patch, check the area often for signs of cracking, and ride it. Steel should give plenty of warning before failure.