Biggest reason why I will never own Minimig because it is completely burned in my brain and will not change is nothing more than UAE running on ARM. However, FPGA is completely custom based, real chipset, in my opinion the new and latest Amiga upgrade had Commodore continued in the line of 68k Amiga. Is why I did preorder for FPGA and did not spend a dime buying Minimig even if it is out already for sale.
Minimig is a re-implemention in FPGA just as MikeJ's FPGA Replay. The difference is that the CPU is in ASIC and RAM is less etc.
A cobbled together A1200 gets to use 128MB (possibly 256MB) Radeon gfx cards which there is no way to do with the Replay.
The FPGA can interface directly to PCI 33/32 and other interfaces can be handled by added suitable transceiver chip or upgrading FPGA with onboard ones (Rocketport etc).
If you don't like your SCSI hard drive you are allowed to buy a new quiet, cool, fast SCSI hard disk for your old Amiga. Or you could just get a cheap silent slow SD card like a lot of ppl do. Or you could use a new slow IDE drive.
Your SCSI controller is likely faster and smoother than whatever Replay has to offer. (Which I cannot remember right now.)
Complaining about SCSI is a really silly thing to do. 
The present drives are almost all either horrible expensive SAS drives which will not interface with Amiga or S-ATA ones that will neither. So you will still need to make do with the SCSI-1 SE narrow stuff that were common with Amiga. Present flashmemory (SD) will beat ordinary Amiga SCSI hardware on Mbyte/s basis.
The reason I bought SCSI is because it has a sound electrical interface, clean hardware API with well defined orthogonal commands, reliable etc. Something P-ATA never managed. Infact S-ATA drives are still second rate when it comes to build quality that's why SAS drives are more expensive. BUT with RAID or ZFS this issue is negated..
