Alan,
I didn't want to get into the specifics of a machine too early, which is why I didn't mention a specific budget. I figure spending about $1500 on a machine (only, without monitors or the external HD array) should put me in a very good place for now and into the future.
I do not shoot weddings or any commercial work, so I don't have a large volume of images to handle, but I do still have LF film scans and stitched images to contend with, and some of those files can be pretty large at times. My digital cameras are 24MP and 36MP.
I have about 2.5 TB in the current MacPro and I am starting to run out of space. I want a much larger array with some redundancy (not necessarily in that specific array, it could be a NAS for a weekly backup). I currently have a Synology NAS that I use for my audio files, for access by the house audio system, so I a familiar with that kind of implementation.
I found what looks like a reasonable starting point for discussion in this blog:
HereIt links to a set of parts.
Here for parts.Obviously, this doesn't address the external HD array issue, so mods would be needed for that. Regardless of the specifics at this point, I think it looks like a reasonable place for me to start thinking about the hardware items.
For example, I expect that 16GB of RAM is sufficient, but I suspect that the 2GB on the video card may be somewhat overkill. I'd probably want slightly larger SS HDs in the machine for the boot/software and cache. Could handle a smaller HD for files if I am going to the external disk array.
Here is a link to what may be a reasonable disk array. As I said, I don't think I'd make this redundant. Probably use a separate array for all the backups.
---Michael