The n100 mini PCs are a fantastic choice for hosting media server software primarily because of its transcoding capabilities.
The i5-6500 you have and the N100 perform very similarly with general compute tasks (though the TDW of the n100 is 6W vs 65W for the same performance). However, the N100 comes with the full Alder Lake Quick Sync engine compared to the Skylake engine on to i5-6500. If you review the hardware encode/decode table here, you can see Skylake HW encode/decode caps out at 8-bit HEVC (HDR 4K content is typically 10 or 12-bit HEVC), whereas the N100 supports even very recent codecs like 10-bit AV1. I recently set up Plex on a N100 mini PC I got for $150 (with 8gb RAM and 256gb NVMe drive included), and it was able to simultaneously do 2x 4K HDR transcodes with tone mapping while also doing a full library scan and credits detection. Of course, if you’re picky about what clients are watching your content to ensure they always watch original quality, you may not need to transcode.
That said, the N100 mini PC I purchased only has slots for 1 NVMe drive and one 2.5" SATA drive. In my case this was perfect because all my media is on a NAS which the N100 now access using a NFS mount, and I can easily back up the minimum persistent data on the N100 PC.
But it sounds like it wouldn’t 100% satisfy everything OP is looking for on its own. If they still wanted a N100 for the transcode capabilities, they may be able to use a USB HDD hardware enclosure to add additional storage capabilities without needing a separate system, but because I already had a NAS for my dedicated storage, it isn’t something I looked into with detail.
Indeed. Sounds like in your case the i5 6500 you have is already suiting your needs, so really no need for more expense. For someone who doesn’t have something like that already though and needs to make a purchase, I’ve come around to generally recommending something like the n100 over a used older-generation processor simply because they cost very similar prices, but I feel you get a bit more with the more recent chips due to the modern HW encode/decode and low power use.