Thanks for your input.
The Comet "SMA-24" is a 1/4 wave whip, so the antenna length is "optimal." Alone, it has approximately 2.15 dBi gain. (manufacturer's spec.- for what that is worth). I realize that 2.15 is no great shakes, but it adds up to a significant gain over the stock duck.
It's an ongoing experiment. Eventually, I will adjust the length of the counterpoise, but I'm not gonna get into tweaking it down to "perfection."
To do so would not add any more "fun" to the hobby, but so far, the gain factor alone has made it totally worthwhile. The only thing I want to change is the color of the counterpoise. The radio and antenna are black, and the counter is white, so cosmetically speaking, that's the only downside for me.
I intend to take the rig on a day trip to the local mountains with a friend. I'll get some signal reports with and without the counter over the local repeaters, but I don't expect the difference to be any more significant than the first test I mentioned. I'll probably mount it to my backpack, "manpack style", and use a speaker mic. This should minimize any interaction between my body and the antenna, but I don't expect that to be much of an issue. I'll report back after the trip with any info that might be worthwhile.
Bottom line, though, is that the efficiency gain versus cost has made this a cheap way to improve the rig's performance.