Mac Pro vs iMac

My guess is the Mac pro will be slightly faster on exports due to a slightly faster clock speed.
For 3d modeling CPU is more important so once again you might feel want to go with the pro.

 

If you're getting paid for your output, then the Mac Pro's performance boost is probably worth the extra investment.

If you're doing this for fun (or only for occasional paid projects), then the iMac should be plenty.

 

Unless you're using Final Cut Pro, there is currently no scenario that warrants buying the Mac Pro. It's the only video editing app that takes advantage of the Mac Pro's GPU & hardware advancements.

The Mac Pro is made for high-end video and animation work. Unless you edit videos all day long (in HD), I can't see any justification for even the low-end Mac Pro because you still have to add RAM, display, keyboard/mouse, etc. Unless you already have those extras, you're approaching $4,500 after tax.

On the other hand, the fully upgraded i7 iMac with 32GB RAM, 4GB video card and 500GB Flash drive with Apple Care costs exactly $3,598.81 including tax (I know, cause I just ordered one).

 

Simplest answer - In general - more $$ buys a more powerful Mac under some set of conditions ... (as always)

At some point, under any number of scenarios, the nMP will be faster and/or quieter than a maxed out imac. This applies to intense CPU loads and is especially true for any multiple GPU capable loads. Whether or not you will ever reach this point or if it matters to you is the real question.