As for 9.x being unstable. I have been running 9.0, and now 9.1 pretty much since 9.0 was in BETA. I've not had a single problem that couldn't be attributed to a hardware fault (had an issue with one of my hard drives). There are two things you need to be aware of for migrating from 8.x I found. One of which is the hard drive device names change in /dev so you need to change them in /etc/fstab if you have them hard-coded. There's a workaround for normal disk slices where symlinks to the old names are created, but this doesn't work too well for dangerously dedicated disks (like I had). Though the more recommended solution is to use labels. Use labels and the names stay the same and there is no issue.
The other change was with IPv6 options in /etc/rc.conf. The way you configure these changed, but if you don't use IPv6 then you don't have to worry.
And yes mailparse is found in mail/pecl-mailparse , I use it myself!