My 000-28EC has a lower action and no intonation problem that I can detect. The end pegs of the guitars were not inserted at the factory and neither fit well. I compared the two guitars with identical Martin M-2100 Phosphor Bronze strings. The 000-28EC has a warmer tone and more volume. Bending strings is easier, suggesting subtle differences in the frets.
Finger vibrato is transmitted better.
Hammer-ons work amazingly well for an acoustic. Riffs flow better, as if the notes blend together. Barre chords on the 000-28EC do not tire my hand as quickly. In summary, both Eric Clapton Signature Martins are beautiful guitars that play well and sound great. The 000-42EC is more ornate and obviously more collectable.