I've been using Macs since 1984 so yes I'm old! I'm currently on a 2009 4,1 MacPro with Mountain Lion OS 10.8.3. Sure, it's beginning to show its age and I'm waiting patiently for the rumored new Mac Pro.
It's tough right now to recommend whether you should wait or try and get by with something less since I won't believe a new model is forthcoming until I see it.
My son just purchased a 27-inch iMac with a Fusion Drive and upgraded RAM and he’s quite happy with it. He runs a music business and it’s more than adequate for his needs. My personal desire is to have a tower unit in which I can easily apply all the mods myself and have the options and power that a Mac Pro provides.
Likewise, I absolutely love my NEC professional graphics display, as its head n’ shoulders superior over the still shiny displays from Apple. That alone is reason enough for me to wait for a new Mac Pro.
Bottom line, if you need something right now then get an upgraded iMac with an external USB-3 or Thunderbolt external drive (or two) and party on! In fact, if Tim Cook doesn't announce a new Mac Pro at next month's developers conference, that's exactly the route I will have to go. In my opinion Apple couldn't care less about Hollywood or the professional markets. Now, if you want a pierced nose-ring that dynamically connects to iTunes and Facebook then Apple would produce it.