I've heard they are good performers at a fraction of the price of Edelbrock. The early ones had some fitment problems as I recall but that was many years ago. I've looked at them in detail at SEMA and they are looking really like good quality stuff. The co. is owned by Jim Davis, former lead guy at B&M for years. I've met him a few time seems like a straight shooter no bs kinda guy. I wouldn't hesitate to use one on my own engine. Their polishing costs as I remember are hard to beat too.
The above is all I can offer. Never have used one personally or seen a side by side dyno comp. vs similar Edelbrock.