I have never played a bad-sounding Collings guitar.
(I owned a new OM-3H for several years.)

They tend to be a little brighter in the mids and highs out of the box than Martins, but the bottom-end can take some time to mature and develop.

If only Martin necks felt as good.
In terms of playability, they are fantastic instruments - doesn't matter which model.

For fit and finish, they are among the finest (as well as small shop) guitars out there. For consistent fit and finish they'll beat Martins and just about everyone else out there, hands down everytime. Bill Collings is a true perfectionist. Gotta like that!