M4 mini's 5 thunderbolt ports are TB4 - 40Gb/sec. That is faster (IOPS - I/O per Second) that any current single SSD can process; you need RAID to have disk fast enough to saturate the IO channel. So external disk expansion / performance is not an issue. AND the M4 PRO machines are TB-5, able to support an astounding 120Gb/sec IOPS. (80 Gbit/s bidirectional, or up to 120 Gbps for unidirectional connections). TB4 is faster than even the internal SSD
FMS is not memory intensive - it runs fine in a 4gb RAM space. FMS is very disk intensive, as well as network bandwidth intensive (in FMS/FMP configs, every record shown moved over the network from server to client and back. The wider the table, the more data that has to move as well).
I ran a benchmark test - same db accessed remotely from 2 different servers. One seriously fast server on a 30 mbit network, and one older i5 on a 100mb network. The i5 was significantly faster in this non-scientific test (which also impacted how I design data structures now - narrow is better, and optimize for lowest network traffic/data movement).
An M4 mini, 256gb SSD, with the base model overkill of 16gb of RAM is more than adequate for most FMS environments, dependent on the size of the DBs you are serving.
Of note is the memory architecture of the M-series processors. Older architectures had processor memory, IO buffer-interface memory, then conventional RAM, each step exponentially larger - and slower - storage.
In the M-Series, 100% of memory has moved onto the processor die, removing the old 3 layer memory architecture from the performance bottleneck. And with SSDs and IOPS disk controllers (PCIe4 interface, NVMe protocol), disk swaps are as fast as memory in the older generation architecture.
10gb networking would be a real performance improvement IF you network infrastructure supports it. Network switches, routers, firewalls, cabling, all need to be up to par for this to be viable. MacOS provides native network bonding, so you can add >1 external USB-C 2.5Gbit adapters and bond them to increase network bandwidth capacity. The 10Gbit ethernet is a $100 build-to-order option.
On the client side - development - my M1 Max Pro box with 32 gigabytes, runs along at about 22 gig consumed, and I typically run a dozen concurrent applications, some with some serious memory needs.
SO, if you are not going to use a Mac Mini M4 as a portable laptop replacement, my recommendation would be a 512 gig 24 gig ram non-Pro mini. It adds about $400 for the PRO, with the distinct advantages of double the RAM memory IOPS and the Thunderbolt 5 ports.
I use a mini with a folding USB keyboard/trackpad, and a 15.6 in USB-C powered stand-alone display (as I never used the laptop where AC was not available) and a 512GB flash drive ($35).... total, less than 1/2 the cost of an equivalent Macbook.
My iPad provides the optional portable second display.
FWIIW, recently the free Oracle VirtualBox has been released running natively on M-Series chips, so running additional OSs (ARM based only) is a viable free option (Parallels is also available).
USB-C cables remains a clusterf___ - power only, 5, 10, 20, 40, 80, 120 Gbit support, display Y/N, audio Y/N. I can't count how many USB-C cables I've chucked and stick solely with TB4 compliant cables, which has all the available features supported.
