As of last night, I've just had my THIRD frame fail on me in a little over a year, the two Redlines, and an '06 Bianchi Cross Concept. I bought the Bianchi very lightly used in January and have a about 1000 miles on it since then. It also failed at the rear dropout although it was the carbon/aluminum bond that failed. I'm not a heavy guy (6'0" 190lbs) and well aware that these were poorly designed or manufactured frames (a mix of bad luck and poor choice by me). It's time for me to move on. I rely on these bikes for transportation. I've been planning to get a Ti frame for awhile but just put it off thinking that a deal on a used AL frame, is worth it. Although I'd planned to get at least half the life I've gotten out of my AL Giant TCR0 (9 summers so far).
I talked with some mechanical engineers and all have the same conclusion, welding the AL frames is just not worth it, especially if I don't have access to heat treatment.
I'm going to give it a try returning the Bianchi to the factory and see if they will warranty it or replace it for a low cost cuz that frame has seen very little use. Thanks for all your replies. I hate throwing stuff away so really I should be riding steel or Ti for durability and repair-ability.