Discovered that my I2C device address was incorrect (at least my understanding). After getting the compass working, I modified the Quickstarter code a but and hooked up the RGB LED Backpack. No success, but then reviewed the Arduino Logic Analyzer capture again.
Found that my 'address' appears to be 0xFE - not 0xFF as expected. Also noticed that when it works, the LA tool I2C decoder is in 'READ' mode. That little bit didn't make sense. I changed the address in my modified compass code and the RGB LED Backpack came to life.
After a very confused Google search session, I contact Pierce at Logos Electromechanical asking puzzled questions. He clued me in on some subtleties regarding addresses. The key was this very clean high-level I2C tutorial that he shared. THANKS!
Turns out the problem was that when I used the bit-bang method, it wasn't accounting for the 'WRITE' bit. So when the L-A tool picked up the address it showed the address's 2-8 bits and the 'write' bit. This accounts for the 0xFF = 0xFE on LA. I need to do some more binary math to convenience myself...