That's why I gave up on a BTO machine 1.5 year ago. I think at that time Apple was busy changing their line-up, so BTOs were extremely difficult to get. I think I waited more than 8 weeks for any progress in China. The plan was to go for a 512 GB SSD. I also made the mistake to order a BTO from a Apple premium reseller. Don't do that, only buy BTOs from Apple itself. Resellers (dealers) are always last in line.
I now have a Late 2014 27" iMac with 1 TB fusion drive. As all my data is on external drives, I only use ~128 GB of the fusion drive, so most data is on the SSD part.
Last year Apple made a big mistake changing the default storage options to:
1 TB default in the 27"
1 TB fusion drive with 24 GB flash (was 128 GB) in the more expensive 27" model
1 TB 5400 RPM in the 21.5" models
That should be 256 GB flash by default, given by the fact that Apple wants you to upload everything to iCloud.
If you try the 21.5" models in a shop, I always think I'm looking at a PC from 10 years ago. Such slow response, it's a joke.
I now have a Late 2014 27" iMac with 1 TB fusion drive. As all my data is on external drives, I only use ~128 GB of the fusion drive, so most data is on the SSD part.
Last year Apple made a big mistake changing the default storage options to:
1 TB default in the 27"
1 TB fusion drive with 24 GB flash (was 128 GB) in the more expensive 27" model
1 TB 5400 RPM in the 21.5" models
That should be 256 GB flash by default, given by the fact that Apple wants you to upload everything to iCloud.
If you try the 21.5" models in a shop, I always think I'm looking at a PC from 10 years ago. Such slow response, it's a joke.