I have owned a 586, still own a 464 and just bought a KG233 (steel). I'm pretty sure the 251 has aluminium lugs, and carbon tubes unbonding from metal lugs is not unheard of.
Regardless of brand or construction I would be concerned with any 20 year-old carbon frame.
Steel Looks can be bought cheap and are nicely made in Italy with Columbus tubing. Saying so you can still buy NOS carbon KGs online if you're that keen.
I have owned a 586, still own a 464 and just bought a KG233 (steel). I'm pretty sure the 251 has aluminium lugs, and carbon tubes unbonding from metal lugs is not unheard of.
Regardless of brand or construction I would be concerned with any 20 year-old carbon frame.
Steel Looks can be bought cheap and are nicely made in Italy with Columbus tubing. Saying so you can still buy NOS carbon KGs online if you're that keen.