What you're trying to do is really pretty achievable with the current mini.
Two displays - you have a Thunderbolt (mini DisplayPort) and a HDMI connector for this. What displays you use are up to you.
SSD - lots of options here - I just installed a Mushkin Enhanced Chronos 480GB SATA III SSD for $450. Very fast and less than a dollar per GB.
Hard Drive - Put in a 7200 1TB drive in the second slot and you have plenty of space for current working audio projects. Move old projects to a larger/slower storage device such as a USB, FW800 or NAS device.
FireWire 800 - you can daisy chain these ports from your audio device or your storage unit. Most have two FW800 ports. Two individual FW800 ports aren't necessary unless speed becomes a real issue.
- If you don't want to put your storage on the same bus as the FW800 port you can always go to a NAS unit, like a Synology or look at one of the new Thunderbolt Docks - like the new Belkin Thunderbolt Express Dock -
http://tinyurl.com/6pvlmmf.
- Also, if you were to use the Apple Thunderbold Display, this gives you a second FW800 port.
All in all I think the mini would work well for you if configured correctly.