Ok so, I've been thinking about your setup for a few hours now and I think we need a bit more info. What are you actually running on that DS920+? If its just basic file storage for movies or photos, you might not notice a massive difference, but for stuff like Docker or VMs, SSDs are basically a necessity for performance. The big thing I always worry about is reliability and data integrity. Most consumer drives lack Power Loss Protection (PLP), which is basically a set of capacitors that let the drive finish writing data if the power drops. Without it, you risk corrupting ur whole volume during a power flicker. Also, NAS environments do a lot of background writing, so you want high TBW (Total Bytes Written) ratings so the drive doesn't just die in two years. If you want stuff that actually lasts and prioritizes safety, maybe check out these:

• Synology SAT5200
• Seagate IronWolf 125
• Crucial MX500 The Synology drives are expensive but honestly, they offer the best peace of mind for compatibility. I'm not totally sure if the IronWolf 125 is the absolute newest model right now, but they're built for these exact workloads. Just dont get caught up in the marketing speeds since ur limited by the hardware anyway. Reliability is king here.

Tbh, the DS920+ is a bit of a weird one because those M.2 slots are officially just for cache unless you're willing to mess with some scripts to make them a storage pool but for the main bays you really want something like the Western Digital WD Red SA500 NAS SATA SSD over a standard consumer drive. The main difference is the *endurance* because NAS drives are built to handle constant parity checks and background tasks that would honestly just kill a normal drive way too fast. I've heard some people say the Samsung 870 EVO works fine but Synology is getting stricter with their compatibility lists so you might get some annoying warnings in DSM. If you're dead set on NVMe, the Samsung 980 Pro is definitely fast but it’s Gen 4 and the DS920+ only runs at Gen 3 speeds so you'd basically be leaving performance on the table for no reason. I’d personally go with the Seagate IronWolf Pro 125 NAS SSD or the Red SA500s because they're designed for this exact use case and fit right into your budget range without much hassle.

Ok so, I went through this exact same internal debate about a year ago when I decided to swap out my noisy mechanical drives for a full solid-state setup in my main unit. Honestly, the biggest thing I learned is that for a home setup, the premium you pay for the top-of-the-line stuff doesn't always translate to a feelable difference in speed once you hit the bottleneck of the network interface itself. I mean, if you're only on a 1GbE connection, basically any decent drive is gonna max that out instantly. I ended up finding some refurbished enterprise-grade drives for way less than the brand-new consumer ones I was looking at and they’ve been absolute tanks. The peace of mind from the higher write endurance is nice but honestly the silence is the best part. I did realize though that for things like Plex metadata or running Docker containers, even a mid-range setup makes the UI feel so much snappier compared to the old spinning rust. Just keep an eye on the TBW ratings instead of just looking at raw speed because that's where the real value hides if you're planning to keep this thing running for years.