iSCSI Storage Array vs iSCSI NAS

Hey guys, I'm looking for a bit of information comparing the speed and capability between using iSCSI on a NAS (Like QNAP or Synology) and iSCSI on a storage array dedicated to doing only block level storage. I keep hearing things such as iSCSI on a NAS has fewer iSCSI features and that because its "emulated" iSCSI, that its much slower than a true block level SAN. Is this a common storage myth or is there some truth behind these statements? I tried googling iSCSI performance using all flash (to remove the drive speed bottleneck) on a NAS with no luck. Is there any reviews or documentation out there showing a NAS being used as a high performance iSCSI target (And when I mean documentation, documentation that's not fluffed up marketing BS from the manufacturer.) Thanks guys!

If you were using SSDs in an older QNAP type device, you probably had SATA II/ other bus limitations at some point. A hardware SAN such as an expensive Dell Equallogic device is going to outperform (in different areas) over whitebox solution such as nas4free based on the hardware you throw in the box. Start with your networking infastructure and look at your IOPS and volume size storage needs. If you are just going to try and saturate a single 1Gbe link, use an old desktop computer to get the job done. If you need 20+ spindles an a pool of just SSDs get some HBAs, a motherboard with multiple CPUs and PCIe buses that can handle the bandwidth, then look at 10Gbe or multiple iSCSI networks for different target paths and get one or two quad port intel nics.