Well, I don't have th specific experience that people like Trek engineers and aerospace engineers have, but my guess is you are correct that the resin matrix is the "weak link" in the frame's durability, simply because it is the softer/weaker of the two materials and is externally exposed to the elements. However, the matrices they use in CF bikes may be exceedingly durable.

As for the feel, as I explained a few posts above, I'd guess the matrix has alot to do with the "feel" inasfar as I imagine the plastic matrix helps absorb (dampen) vibration.

But a composite material is best viewed not only as to its individual components (CF and matrix, which may individually fail), but also as the synergistic (i.e. greater than the sum) properties of the materials in combination. That's what a composite material is -- two different materials in combination to produce a net result better than or unobtainable by its components individually.