Understanding hardware choices and balancing "performance" for network limitations

[Pavocracy]

Hey all,

so my first attempt at setting up a truenas server didn't go great, mostly because i fell into the WD red trap where they ended up being SMR, and secondly because i didn't really consider what kind of bottlenecks i would hit even if i did have better hard drives. When i initially setup my server, i used 3 mirrored vdevs of 2 drives each because all i cared about when i was doing research was pure IOPS.

But over the year or so I've had this machine running, I now realize that actually its likely that my gigabit networking (and specifically using SMB/NFS) are going to be a bottleneck anyway. Given that these limitations are not fixable for me, for my second attempt at building a new truenas server to migrate to, I'm trying to do my research and find out what is a reasonable configuration for these limitations, and so wanted to sanity check my conclusions here if that's ok?

Reading around performance threads, The conclusion's I've come to are:

1. mirrored vdevs are going to lead me to potentially wasted space, since a RaidZ2 will saturate a gigabit network. Is this correct? and if so, is there any real difference between different Raidz2 setups, like 2x 3 disk vdevs, 2x 5 disk vdevs, or a single 6 / 10 disk vdev for general performance (balancing throughput with IOPS)?
2. IOPS are not everything, and in real world workloads, throughput and random reads will likely be the better thing to target, especially if its going to be so easy to hit a networking limitation. So putting in effort to setup caching with SSD's may actually be more impactful than worrying about the main pool configuration?
3. record size and compression type can make meaningful impacts to performance over a network when the workloads contain large files (for example when truenas is the centralized server for video files). My use case for truenas is first and foremost a storage server, to backup my important data, so copy once and leave it forever. However, i do also have a jellyfin server running in a jail that has all the media served from it, and while this isn't my most important use case, i do want to make sure I'm not leaving performance on the table due to a simple pool setup issue. So are the record size and compression types important here?

I know there is too many edge cases to have a blanket recommendation for performance considerations, otherwise everyone would be running the same setup! But as i mentioned, I'm trying to do some more diligent research this time around and it would be great to get some input from community members around the above points. I really want to make sure I'm maximizing my choices purely around the limitations of a gigabit network setup accessing the truenas pool via SMB / NFS.