I'm choosing an SSD for a midrange build used mostly for gaming and general tasks, with some light video editing and occasional large file moves. A DRAMless NVMe drive would save some money.
Is the difference likely to be noticeable day to day, or mainly during long transfers? What should I look for when comparing drives?
A decent DRAMless NVMe drive is a reasonable choice for that workload. Game loading and everyday responsiveness are unlikely to change dramatically just because a drive has onboard DRAM. The occasional large transfer might take longer, but that doesn't make the drive a bad fit.
I'd put the savings toward capacity if the alternative is a smaller drive. Just check reviews of the exact model and capacity rather than buying solely based on the advertised peak speed.
DRAM and sustained write speed aren't quite the same issue. Some DRAMless NVMe drives support Host Memory Buffer, or HMB, which lets them use a small amount of system memory for drive management data. That helps compensate for the lack of onboard DRAM, but it doesn't turn system RAM into a big write cache.
Long writes can slow down after a drive's fast write cache fills. The amount of slowdown depends on the NAND, controller, capacity and how full the drive is, not just whether it has DRAM. If you move big video files or game libraries, look for sustained write tests and check how the drive performs when partly full. A DRAM-equipped drive isn't automatically immune to a slowdown either.
I wouldn't apply the same rule to every kind of SSD. Modern NVMe drives may have HMB, while SATA drives don't use that feature. For a SATA purchase, especially a boot drive, I'd pay closer attention to reviews of DRAMless models rather than assuming they'll behave like a good DRAMless NVMe drive.
Check the NAND and endurance rating too. TLC is generally preferable to QLC for heavier writing, and some cheaper DRAMless drives use QLC. That doesn't mean every QLC drive is a bad buy, but its sustained write performance and rated endurance are worth comparing with a similarly priced TLC model.
If the editing or backups grow into frequent, large writes, spending more could be worthwhile. Waiting occasionally is different from sitting through slow transfers every day. I'd compare sustained performance and price for the specific drives, rather than treating onboard DRAM as a guarantee of a better result.
Answers are reviewed before publication.
4th.wall.maybe:
Transfer speed also depends on the other drive. A faster destination won't necessarily help much if the source is the bottleneck.