Incidentally, while messing around with transfer functions and sensing matrix elements this evening, I was able to sideband lock straight onto REFL33 I&Q.  The settings were all identical to Koji's ELOG, with the following differences:

Input ports:
REFL33   WHTN: 30dB demod phase +125.5deg (tweaked from 135.5 to minimize MICH in I)

Input matrix:

REFL33I x +1.0 -> PRCL
REFL33Q x +3.0 -> MICH

Servo:
MICH OFS 0 / Gain 1/ Limitter ON (Oscillations occurred at 1.3)
PRCL OFS 0 / Gain -0.04 / Limitter ON

Output matrix:

MICH ITMX -1.0 / ITMY 1.0
PRCL PRM 1.0