Upgrading from a Western digital pr4100 to a qnap for plex server ?

Hi, I'm very new to Qnap been reading plex's requirement spread sheet for the best systems to play 4k UHD videos and the best out there seems to be the qnap TVS-1282T3 I like the features and I'm hoping it uses plex to it full potential, if you have any thoughts on that would love to hear them. another question is I am using tons of sing external Hardrives as cold storage for my western digital pr4100 Nas and would like to have one big storage array preferably 8 top 12 bay external hardrive can the expansions TX-800P be uses in such a manner where can plug it into my PC and it sees it as one big drive or is there another Qnap product I should be looking at ? any and all advice would be helpful. Best regards!

Synology and Qnap models do allow you to create a JBOD volume. This means that all drives are merged together in one big storage space. But if one drive fails, you lose data from that drive. If you use SHR you can combine different capacity drives into a RAID. You can play with it here https://www.synology.com/en-uk/support/RAID_calculatorTVS-1282T3 has been the best Plex NAS for a long time. Now there is also a new TVS-h1688X and TVS-h1288X with an embedded graphics chip. This could be an option too.If you want something where you can remove and add drives from the system then Asustor models allow archive function to do so.I hope this helps.