I use my M9 all the time, and I love the sounds in it. I have never had any problems with it, so I would recommend the M5.

I also have a DD-20 that sounds really good. I should sell it - I can't fit it on my pedalboard and I use the M9, so... If you ever see a used DD-20 for a good price, it's a really good delay pedal. The modulated delay is gorgeous.