Max out an old Mac Pro or jump to 5k iMac

The company I work for is looking into replacing our old Mac Pro towers with 5k iMacs for editing (FCPX and Premiere Pro). However, there is a debate as to wether or not we should just repurpose the old towers and "wring the life out of them". This all started with Scott Simmons article that can be found here: provideocoalition.com/ssimmons/story/wri...old-mac-pro-tower/P2

Money isn't really a consideration at the end of the day so what's the best way to go? The 5k iMac or revamped old Mac Pro towers?

Hi Ray,
Welcome to the forums.
Well this is a controversial topic with lots of opinions. All of them 100% correct
You don't say which of the older towers you have and how they are currently equipped, so suitability will vary.
There is an ongoing thread here that talks about different configurations of MPs especially modded with dual GPUs.
www.fcp.co/forum/hardware/18250-brucex-t...-cut-pro-x-benchmark
Also I really like the testing done by BareFeats as they compare lots of different systems.
www.barefeats.com
The Scott Simmons article is a pretty extreme modification, and requires lots of $$$ and maintenance to keep working, so assessment of groups abilities applies here. I like modding MPs, but I doubt I would go to those extremes. As sad as it is, I think the cheese grater MPs have a some what limited life, but I think the nMP has not reached primetime yet either.
What type of work you are doing should also play a part in choosing a system. Larry Jordan has a pretty good article about matching codec/workflow to computer systems…
www.larryjordan.biz/app_bin/wordpress/archives/2559
Assesing the 5K iMac vs an older tower adds lots of other comparisons, some technical, some esthetic. Can't argue against the screen in the new iMac, especially if you are doing 4K video. You do trade off expandability, upgrades to hardware, mobile CPU/GPUs vs enterprise desktop components going the iMac route. Still I think the new iMac is a very capable machine. Just stuff it with ram.
Might want to purchase an iMac, mod an older tower with a dual GPUs and a ssd or PCIe blade boot drive. and see who fights over different models.
Hope this helps, Greg

Thank you Greg. This is very helpful and will check out the links you provided. We have 4 or 5 old MP that are varying models and configurations. That's why I didn't specify any of that info.