To the OP
If I remember, you are a bigger guy who also seems to have the time to get out and ride hard, frequently. I think with that combo, bikes are going to be somewhat consumable. Maybe that crazy Mixte will hold up but the lighter and more legit serious bikes will eventually reach a retirement age.
I’m 140lbs and never been over 150. I’ve only cracked 2.
A Cannondale Killer V that I noticed the crack on inspection. Could’ve been like that for a long time. This was the mid 90’s in that weird era where there was a new experimental version of the same frame geometry every week. So stuff tended to break.
The other was a Felt B2 from the Answer days. Again, a small crack I noticed on inspection. They actually re-welded the frame and sent it back to me. It was fine for many Tri’s after that.