Yep we did it with no issues. No data loss. Only called support when I thought that the post install centos scripts had hung, but it turned out the idrac was just crazy slow.
We have a Packet and Log Hybrid, SA, ESA (four appliances)
In terms of time, I did SA via iDRAC and I had not read this and it took around 12-14 hours to upgrade SA. (very stressful night) I then did all the other hosts with a USB stick and it took about 30 minutes per host (not including the backup scripts, which didn't take very long)
Very good experience all in all, I was quite hesitant initially and put off the install for quite a few months, but I just bit the bullet and did it, and everything came up Milhouse.