iMacs from what I read over heat. Never heard of a Mac Pro doing so. MacBook Pro, then yes they get very very hot. You can't really kill a workstation. Unless you cut off air and put it in one of those "hutches."
Maybe your very expensive could have saved and gone with less, donno what you go but $1889 and up, just don't buy what you can buy elsewhere (RAM, hard drives and such).
Final Cut Pro-X is due for a refresh.
http://www.macperformanceguide.com really answers a lot of questions on upgrades, configuring, and performance.
You didn't really tell us what your real choice was, just basic outer shell. 4-core? 8-core? the 6-core is the sweeter of them. The 12-core might be unjustified and not enough unless it is used to bill hours, a lot of hours.
How to do a 6-core and save:Mac Pro 2010 6-core 3.33GHz
Refurbished 2.8 4-core $1899
I bought a top-of-the-line iMac in 2008 to do video editing. It got very hot. After 1 year the hard drive failed and then after 2 years the graphics card failed. I decided to bite the bullet and get a Mac Pro. I bought the bottom 2.8 version and have been upgrading it with extra RAM, SSD, etc. I'm about to upgrade it to a 3.33 6 core. It has been rock solid and I haven't noticed any loud fan noise. I am currently running FCP X on it. So, from my experience, you have made the right decision to go with the Mac Pro.
I got the 3.2 GHz quad-core with 8MB instead of the standard 6 MB. I'm a noob when it comes to how to build a computer... I just want to be able to use my programs without having to get my patience tested by a computer. Thankfully my bf was there to help me purchase my Mac Pro because the apple representative was trying to convince me to upgrade to another graphics card. Little do I know, this is mainly for people who play video games or create video games..Then the day after I was having buyer's remorse, unsure if I should have bought the iMac over my Mac Pro. Like I said I'm a noob when it comes down to how to decide which is better. But your response helped! Thanks so much!!
RAM is just user installable part that costs 2x from Apple as buying it yourself.
Building involves choosing motherboard, processor, power supply... everything.
RAM and disk drives - and grapic card - are all eash to do and designed for ease of use.
The "2012" base then. And decent system. A lot is when you get over the $4K mark and get into an 8-core or above. Even the 6- core 3.33GHz which I would have recommended is still only $3K but 50% more processing punch.