I was with M6 for one year. It sometimes it worked well but recently they had a one-week crash. Here is my experience with M6.net

Uptime: The uptime is pretty good.
Email: They had huge problems with the email in the past, now they solve it.
Administration: The CoPanel is a disaster. You see more errors than useful information.
If they have a breakdown they will restore your web sites from very old backups and they won’t inform you.
Speed: HTTP speed is between acceptable but PHP speed and SQL is a DISASTER. M6.Net is the worst solution for a forum live VBulletin or PhpBB.
FTP: ftp keeps disconnecting you after 1-3 minute(s) without warning. Upload speed is max 20-30KB/sec (even thought I am able of 100KB/sec).

SUPPORT: Pray to God that your account will stay out of trouble. Of course if you are in trouble, there is nobody to help you. Recently all my web sites were down for 5 fucking days and I was impossible to speak with somebody for real! They pretend to have phone support 24/24 but actually a guy from India with a rudimentary English answer only few hours in the middle of the day, and not in weekends. So if you want to see if I am telling the truth, make a phone call to ‘Technical support’ in the middle of the night (US time). Also send a ticket in the night and see when you get an answer.
So… my tickets were still unresolved after 5 days. All they answered was "Our stuff will handle your issue as soon as possible" and "Our stuff will reply soon". I bet was an automatic message.
Basically, there is no support. AT ALL!

Conclusion: If you want to run a very basic web site (plain HTML, no DB – for example holiday/family photo album) and you are not in hurry, M6.net is acceptable. If you want run a business web site, than obviously this is not good place for you.
1 star out of 10.

Now I move my site to a different host. Wish me luck.

PS: did I mentioned that they lost my forum’s DB ?