with 9k jumbo frames I can burst read 32mb/s very breifly and it settles to 25mb/s burst writes 22mb/s and 16mb/s constant. I am using a raid0 config, so my numbers should be lower than single disk or raid 1 config. I also recently moved my nas to a different room where the cable run with meow5e is twice as long, I took a bit of a performace hit there too

I would say you are getting max performance from your DNS
It is normal for a difference in reads vs writes, as writing to the disks uses more CPU power (especially with a raid config). The CPU is the bottleneck here.
enjoy.