OK: some follow up...
I booted BT4R1 direct from USB on a different machine (eeeBox, Atom N270) and tested several wireless cards for injection... Results were very interesting.
Atheros 9170 and ZD1211 injected "out of the box" - Atheros had worked on another machine (Latitude 6410) but ZD1211 didn't.
RT73, and RTL8187 passed the "aireplay-ng -9 mon0" test but didn't actually inject on my test network, at least not so far.
RT2800 does not pass "aireplay-ng -9" with out-of-the-box R1 driver.
A fresh boot was needed between the tests to get the drivers to run correctly.
Apparently success is somewhat dependent on the hardware platform.
Updates (using the update.sh tool posted here, as well as "apt-get upgrade", etc, as well as recompiling from the latest sources, break many of the drivers that work on a "fresh" install.
So another question: other than manually extracting from the stock image, is there a way to easily return drivers to their original "out of the box" versions?
No amount of patching and recompiling (either with the compat-wireless version supplied with R1 or later versions) will solve the "channel -1" bug in aireplay-ng - so far.