Well Bang... I've actually tried both ways. Both worked for me, but I like the post fader. Seems to me (IMHO) that the noise level was less and the levels seemed to "respond" better. Might be due to the fact that the post fader level is +4 going into the compressor ,which is +4. Where in the inserts are -2 and even if you go into the compressor at -10, seems to be a bit "odd"! Most compressors I've seen, has a "switch" for -10 or +4, not -2....

.! But all in all, it'll probably come down to the quality of the compressor!..