@edmund - The volume would work, it just wouldn't repeat. The problem with the Sony VL-900, which I verified with support, is that if you teach the control something on the volume buttons, you lose the repeater function. So it was able to broadcast the signal, it just didn't repeat it, which was the problem. (Again, when I say it "wouldn't repeat," it isn't that it wouldn't learn-and-replay a signal, it's that when I hold the volume button down, it doesn't continue to send the signal over and over the way I would expect.)

@39 Cent Stamp - Tried different durations of holding the button when teaching the Sony VL-900 and never could get it to succeed. I was able to get it to turn the volume up one notch... but to continue turning the volume up required another key press. I ended up jackhammering the volume buttons to increase/decrease the volume by any significant amount.

In the end, I got the Radio Shack 15-135 remote which does correctly handle my TV and properly deals with the volume. (I was actually amazed at how many things it automatically just "knew" based on the code. I only had to teach it ONE thing. Very cool.) At $22, it was just right for the price range and has more hard buttons than the VL-900, which is nice. With the VL-900 I was having to drop functionality and do a lot of "button repurposing" (e.g., the "Record" button became the "Exit" button on most menus).