Art V,
Thanks for replying.
The read/write speeds (from Apple) of the 512GB SSD are the same as the 1TB SSD. I keep a really clean computer, so I think the 512 should be more than adequate for me.
I don't do any film editing or Photoshopping where I would need the extra headroom for disk cacheing, so for now, I think the 512 should be adequate. The 512 GB SSD is still a money upgrade from the base storage which is a 2TB Fusion drive and which has only 128GB of SSD storage. At a later date I can always add an external SSD drive via Thunderbolt 3, which is very fast.
For instance, I have over 2 TB of music, none of which is on my computer, but on an external drive which is hooked to my router. I can transfer all my digital photos to an external, which also lowers my need for in-computer storage.
The memory from OWC or from Crucial are the same specs as Apple's; 2666MHz DDR4. ( I did talk to an OWC tech).
Apple's memory cost upgrades:
16GB- $200
32GB- $600
64GB- $1000
So for about $220, I can do two 16GB modules and get 40GB total.
At a later date, for another $220 I can add two more 16GB modules for a total of 64GB
So it's $440 vs. $1000.
The one nice thing about the standard iMacs vs. the iMac Pro is the ease of memory upgrading. The iMac Pro is quite complex to upgrade the memory because it doesn't have the memory access trap door like the standard iMac. The internals of the iMac Pro are in different locations than the standard (I believe it has something to do with the cooling).
Anyways, I hope our conversation can also help others who are in the upgrade cycle.
Thanks