Re the recording: My recent recordings have been done using the built-in camera and mic on my new MacBook, with both my voice and my guitar miked and fed through a PA system which produced, in the live setting, a very balanced sound with good volume. But although the sound coming from the speaker seemed fine, the guitar sounded weak and tinny on the recording, much more than my voice did. The last recording was done with a direct-in on an acoustic/electric Sigma guitar (size and shape like my Martin 00018 but with a cutaway), and even with that, the guitar did not come out strong on the video. The two earlier ones were done with the Martin 00018 -- which, BTW, tends to favor the high strings more than larger body Martins like Dreadnaughts do -- just miked, and I think maybe the mic wasn't close enough to the sound hole.
What's odd to me is that I have recorded live music several times on my MacBook with no amplification used on either the voice or instruments (mine or others') and the laptop placed at least 6 feet away from the sound source, and both the voices and the instruments could be heard pretty well. When I used the PA system, the overall sound was louder.
But my sense that my high strings are not carrying as well as the lower ones comes from live jams too. I often find that when I do an instrumental break in a jam with several other instruments, the melody that I'm playing isn't very audible above the other instruments, especially the 2 or 3 higher strings. That's another reason I was interested in trying heavier G, B, and high E strings.
As for my technique, I'm sure that plays a part. But as arthritis is increasingly affecting my right hand, not just the left, I find that some of the subtler aspects of technique, such as plucking fast and with even tension, are getting harder. I don't know how much I can compensate for the unevenness of volume just by practicing.
I really do appreciate all the feedback and suggestions from you folks.