Picking a stable Pix v7 code

My inquiring in this newsgroup into upgrading a Pix with minimal downtime has led me to wanting the new features in the v7 code that promise a near downtime-free upgrade process.

I've run 7.0.2 and 7.0.4. I upgraded a 525 running 7.0.4 to 7.1.2 only it automatically reboot every 4 hours due to a bug in the inspect http code. I've been told that 7.0.4 has been the most stable to date. I also see that 7.2.1 is out. I'll of course read the release notes and known bugs on the Toolkit site for all current releases. In lieu of a problem I find there what is everyone's general feeling on the most stable v7 Pix/ASA release to date?

The Pixs are 2 pair of 515e, VAC+, 128MB of RAM (this will be upgraded to 256) and are running with a UR license. They are currently running in A/S mode.

Behind each pair of Pixs is a Telco soft switch. Currently signalling traffic between the switches must pass through a pair of failover Pixs onto a VPN tunnel and to the other pair of failover Pixes. This traffic is purely signalling at the moment. SIP and RTP traffic also comes through the Pixes from telephone over cable customers. There isn't much of a translation table to maintain.

Given that a phone system depends on this setup we must maintain 5 9s or better which is why I'd like to upgrade to v7. I need stable but I also need a decent upgrade path. v7 affords me a decent upgrade path for minor updates (7.0.2 to 7.0.4 for example) but not between "major" releases such as 7.0.4 and 7.1.2 or 7.2.1.

I plan on redesigning this network to not require the Pixs for soft switch to soft switch communication. This is a poor design. The Pixs will be required for customer to switch interaction though.

Thanks for your input, J