Ya, I got both and I have an opinion. I like the M300 much better. The PCM91 is very good but the M300 is just better. Richer, deeper, bedtter.

I like anything LEXICON. I believe the 300 is an older unit which its high frequency response may not extend as far as the newer unit and perhaps that's why the previous posting liked the lusher quality of the slight lack of high frequency response which can be quite beneficial if it's not actually required. Some People like a Warmer Reverb As Opposed to a Brighter Reverb like an old EMT plate which tended to " sizzle" a lot due to its hefty preemphasis curve and the nature of the beast. Something I used to like a lot because it was cool but certainly not applicable all the time.

I'm still using my old PCM 60 and 70 and still love them.

Living in the eighties
Ms. Remy Ann David