Do you think if you call Apple they will let you upgrade to a Vega II with just difference cost?
I tried that. The answer is no.
The only options were to return or exchange the system. Exchanging means going about 2-weeks without, so I opted to purchase a replacement system and then send back the original after the replacement arrived.
Despite what the website says, it takes only about 7 days from order placement to delivery (at least to WA state anyway) and Apple allows a 2-week window to ship back, so there is no gap w/o machine. You can also arrange for return to be picked-up from home w/ carrier, so the entire process is pretty painless except for needing to setup machine again (I prefer to always clean install as opposed to restoring from backup).
If OK going to and Apple store these days, then can get time w/o system down to about 1-week going the exchange route. The credit towards new replacement machine is processed immediately, so then just the time for it to be built and delivered.
IIRC,
@choreo purchased from B&H. So, the only option would be to push on Apple support harder to get creative about a resolution. At the price Apple is charging for Mac Pro and for how we are using these machines, I wouldn't give-up until satisfied.