[Update]
I managed to do some preliminary test, by connecting 4 drives (2 x SAS, 1 x SATA3, 1 X SSD SATA3) as pictured.

I have tested using an Adaptec 71605 (4 x 4 8643 ports) and found some strange "happenings".

When connected directly into the Adaptec card, all seems fine. But when connected through the AOM-SAS3 external 8643 to 8644 adapter, the SSD SATA3 strangely "drop" to 3.0 Gb speed, although the SATA3 HDD remains at 6.0Gb:

https://imgur.com/a/KDm4AdI

Now this is really strange.

I'm also found a 8644 16e 12Gb HBA card that must arrive. I will update the post

Thank you gargravarr2112 for your answer.

System 1 is with a PTJBOD-CB2 already configured. That PB was 100€ expensive (original Supermicro).

Yes, there are, but under 600$ are not find. The two supermicro CSE836 cases were 350$ both, as much as sas2/sas3 backplanes could be found on eBay.

Thank you. Took me a while to select all the layers.

It's not sas. It's SAS, SATA, and SSD. That's the reason for a straightforward backplane.

It was late, and took me a while to layer everything in the picture... and less is more.

Thanks to everyone who answered. I didn't provide any details because as the saying goes, one picture is more than 1000 words worth..

Yes, the "System 1" is a JBOD with a SAS/SATA 16 Ports backplane, that will run a mix of sata/sas/ssd's hard drives. This must go with no witchcrafting to the "System 2", as .. pictured.

I also consider a 4 x 8644 external HBA, but until now I only managed to find some LSI/Broadcom/Avago cards that are too hot and maybe fake chinese ones, with no guarantee of data/firmware/functionality. And the prices are also too high.

I,m already over my buget.