DS923+ configuration - Drives/Cache

[Enquiries]

Greetings,
I'm convinced me that the following NAS is for me

DS923+ with 4GB RAM
10GbE network card
RAID 10 array

I'm looking for redundancy, reliability, and I/O. My usage case is fileserver, media server, and video workflow. No transcoding or VM. Maybe future surveillance video.

I'm need to populate this basic Synology NAS:

DS923+ with 4GB RAM
10GbE network card

WD PRO drives are 7,200 RPM and PLUS are 5,400, I don't know which are more reliable and/or faster in RAID10 arrays. Also wondering if adding an NVMe cache is a game changer.

Here are three potential configurations:

> Configuration 1 (slow HDDs)
3TB WD Red PLUS (5,400 RPM)
Cost = $990

> Configuration 2 (slow HDDs, plus caching)
3TB WD Red PLUS drives (5,400 RPM)
SNV3410 400GB SSD Cache
Cost = $1,150

> Configuration 3 (fast HDDs)
2TB WD Red PRO drives (7,200 RPM)
Cost = $1,090

Q1) Any standouts for reliability and/or I/O?
Q2) Would additional RAM help I/O at all?

Thanks!