I´ve tried a Surefire L1 (old style) with a Seoul P4/McR 18 reflector, a Surefire L1 (old style) with a Cree/McR 17 cutdown reflector and a Surefire L1 (currend style) with a Seoul P4/McR 20S reflector.
Minimal more flood, minimal brighter but no great difference to my Milky M-L1.