I can’t think of a use for a dedicated 64GB pool of fast storage for a home server running Seafile, databases (when exported to SQL syntax) don’t excede 700kB on my home server (1,7TB used, 6 active users and about 10 libraries per user) so those are probably just on RAM all the time:
Unless you want to use the SSDs as some sort of cache I don’t recommend you invest on that, maybe get another drive for the RAID and do RAID5-6.