Expect slower speeds and worse latency with ECC.

Probably 3200MHz CL22 or 2666MHz CL19. Your current 3200 CL16 is faster than almost any DDR4 ECC stick you can buy.

Consumer RAM is binned for speed and tight timings. ECC RAM is binned for stability and error correction. That means looser timings and often lower clocks. Most DDR4 ECC sticks max out at 3200MHz CL22 if you’re lucky—many are 2666MHz CL19. You’re going from a fairly fast kit to something that feels like a step backward.

If your workload actually needs ECC (file server, ZFS, long renders), the tradeoff is worth it. If you just want more RAM, stick with non-ECC and save the money.