As someone who has multiple stamps I'll make a simple statement. Firing a full auto weapon loses some of its mystic in fairly short order. My experience has shown me that shooting F/A starts out as quite a rush but becomes both common place and relatively expensive in just a few outings. I'm not saying someone shouldn't have a F/A weapon. I believe they should, if for no other reason than they legally can (You must abide by the laws here).
That said, my gut tells me that somewhere down the road, this product will find itself in the same category as Akins product. No tip toeing around it. It seems that just about any good idea that has been designed to legally skirt the F/A laws and achieve this goal has been squelched by the BATF.
This product is a simple design that seems to do it's job fairly well. I see no reason it would not perform as advertised without significant problems (mind you I've never used one). The claims of hard to hold on target or inaccuracy would largely be the same as any full auto weapon. Automatic weapons climb and can be tough to keep on target, end of story.
I believe those who decide to purchase one of these should make sure they keep abreast of the product, company and what the ATF does in the future with respect to this product's legality. It would be a shame to find out the hard way you are no longer eligible to own any firearms and that 10' X 10' isn't a lot of space over a 10 year period.