My personal choice is to keep the 5,1 as long as it can work decently. And hope the coming 7,1 is an upgradable computer (or at least not thermal limiting).
+1 for the price per £ they are still the best option.
I keep trying to remind people that having 4 technically 6 drive bays (removing the dvd drive) and another possible few using PCI cards that it saves the average user roughly £1000 buying an external array and populating it with discs.
It is an old machine but I ordered an RX580 8gb and I can just stick it in and keep it going. How novelty!
Ok compared to the newer benchmarks of the imac pro they dwindle some, rightly so its £5k and 9 years newer.
But still my mac pro is on par with an equivalent spec hex 6,1. Ive been able to upgrade the processor, ram and graphics card and as a professional photographer and run around 8TB of data per year. In the field you have a duty of care (eg weddings) to ensure data is safe. When you need to duplicate that data once as an onsite back up and then again as an offsite these arrays start to add up.
Its a good machine and is still supported by apple so runs the newest of all software and well and is super stable! My twin apricorn velocity pci cards with 2x 850 evos run 800mb reads and writes. You can add new wireless and BT cards to make airdrop work etc etc
Essentially my initial investment has lasted me the best part of 8 years so far, mostly because apple hasnt replaced it with something similar. Although I have upgraded it ive had no issues at all, nothing has failed and every upgrade has just worked...
I cant say that the iMac pro will be the same if I bought one.
I have to say the Pro is feeling its age and im in the same camp that I hope apple makes something along the same lines, however doubtful. Then I will make a decision.
My mac pro has had 4 different graphics cards in its life, at the time the graphics card it shipped with was a really good card like the iMac pro... but would you really spend £1000 buying an external enclosure and another card to fill it when you want a new one? Regardless of what people think an external enclosure is a super niche item and I cant see them being mainstream any time soon.
Eventually it just costs you more money and its not cheap to start with, its not the same proposition.
Then again its not the same idea, could we call it a pro consumable machine...?
Either way in my field, image making does not evolve so quickly so my needs dont necessitate the best of the best. When im making motion graphics thats a different need all together so I like the fact the Mac Pro can and has grown with my needs.
Im pretty sure im not the only one in this situation. There will be a lot of prosumers as well as pros and plenty of people with lots of data that dont necessarily want to spend thousands on multiple TB3 arraids and 4 year later be defunct by a newer version of TB.