SRC CLAIM to be "high end". Their retailers tend to claim the same. But it's not because someone says something that it's true. I can say I'm a ninja. My friends can say I'm a ninja. It certainly doesn't make me one.
I would consider SRC the high end of low end guns / low end of mid-range guns at best. They used to be bottom of the barrel a couple of years ago. They've made improvements all around in terms of their externals, parts quality, etc, but sadly, their quality control isn't one of the improvements made. If they actually put in the QC work to make sure all their shim jobs were accurate, parts were well lubed, wiring intact, and everything in working order before guns left the factory, I would consider them towards the high end of midrange. An AEG is more than just the sum of its parts. You can have the best and most expensive parts on a gun. If it's not assembled properly and doesn't work right, the gun is still a piece of junk, regardless of the quality of the components that make it up.
To someone who knows how to fix guns, it may take a little work to reshim, lube and perhaps replace an inexpensive part or two to make it into a decent and gameable gun. Out of the box, they'll be hit or miss, where you can have non-working guns or massive failures that will destroy the internals. Other times, they'll work just fine.