Thanks to both of you for your feedback. I was tempted to look into current production tube amps, but my budget stopped me cold.
Had a chance to listen to both amps the past week and ended up buying the D125. More extension from top to bottom, although the D115 Mk2's midrange was one of the best I've ever heard. Vocals have a "you are there" feel to it.
The D125 was, overall, more satisfying to me for a wider range of music. I do listen to, and enjoy just about every type of music. The D125's mids are not quite as natural and sweet, but sounds more like a modern amp. (It is the stereo version of the M300's,at the time.) Its hybrid design also seems more user-friendly for tube replacement and over-all maintenance.
Thanks again.