Qtx, I know you have settled on the Synology, but I would agree with the slower network performance on the Qnap as well. I have the Qnap TS-412 and noticed a big difference between it and the HP Server it replaced.
However the difference in my electricity bill has outweighed the speed difference
I'm happy with my NAS and especially like the Amazon S3 client for cloud backups.
Cheers.