I have 96 strings of M6 LEDs and when I bought them they sounded like they were the same as M5. What I figured out after I had put them up is that they really are larger than the M5.
The question is which one? I thought the M6 was a little large coming from minis. Besides the size, do the M5 have a smaller LED? Are they noticeably dimmer or the same brightness?
I still have enough minis to give me headaches for a few more years but I'm feeling the need to start switching and I have more strings than I care to count so I want to get it right.