I don't think you are loosing any image quality with the greater tilt. What you might be getting are reflections that you would not otherwise see if the tilt was at about 10 to 11 degrees. However, the only way you are going to see for sure is to adjust the tilt, which sounds like it is difficult. Also, comfort should be the same since the angle you are looking up won't change regardless of the plasma's tilt setting.

What kind of mount do you have? Most of the tilting universal mounts out there allow for the plasma to be lifted up an inch or so and separate the two parts of the mount; the part connected to the wall and the second one connected to the back of the plasma. The recess shouldn't prevent you from removing the plasma (if so, how could it have been installed it in the first place?) and changing the tilt. That Panasonic weights over 80 pounds so you need a strong friend or two to safely remove it, but if done carefully I think you should be able to make a tilt adjustment. If you had it installed I'm sure you could get the installers to come out and make an adjustment for a price. Just my 2 cents.