We've got Persistent Disks aka PD (logically similar to EBS / network storage) that come in both a "hard drive" variety and an "ssd" variety, as well as local SSD.
I assume you're talking about one of the PD products, most likely PD-SSD and comparing to one of the EBS offerings (either the new one or a piops one)?
If so, unlike traditional EBS, PD scales throughput according to disk size [1]. You get 30 IOPS/GB up to 15k or so. As far as latency goes, what instance were you testing on? Your VM's I/O competes for cycles with your vCPU (this is true of all KVM-based virtualization), so if you spike up your CPU you can easily "starve" your I/O threads or vice versa.
As to your DNS question, I'll have to look into that. But where are you trying to communicate? (I mean clearly you found me, but I mean where else)