Upgrading from a DS213se, 2 x 4 TB, 1.6 TB movies and 250 GB photos. Backingup to USB attached 4TB HDD. Based at home. Want to upgrade for improved speed and capcity to use as Time Machine backup destionation for 2 macOS laptops and a MacMini. Will also host files for two users, about 50 GB each. old DS214se will become backup to new NAS. Will plan on max synology RAM to protect warranty and new NAS drives. I expect that the process for migrating data to a 2 drive unit is different from a 4 drive unit. Need guidance on that process after purchase decision is made. Could do DS218+ with 2 x 8 TB drives or DS418+ with 4 x 4TB drives. Suggestions and comments? Am I missing an important issue obvious to a more expereinced user?
Yes, your options then will be DS218+, DS718+ and 4-bays like DS418play and DS918+. If you do not plan on expanding the bays then stick with DS218+/DS418play. You can still upgrade the RAM and have expansion as a separate volume. Backing up is not very resource demanding task. You will be able to create two separate shared folders for each computer backup files. And there will be still enough of computing juice left to explore other amazing stuff you can do with Synology.
I hope this helps.