The trouble with gloves and any other protective equipment you wear on your bike you will never know how good it is at protecting you until you need it.
No matter how many lab tests and suchlike are done the only real test is when you actually crash on the road and every crash will be different, there are so many variables such as road condition,speed, how well the item fits you, the used condition of the item and probably a great many other factors.
Like most people I usually assume that more expensive means better but how can you really know? Those cheap gloves you bought in the sales, and most of us have done that, might be just as good at protecting you as the latest £250 must haves the all the magazines tell you to buy.
Its your body and its your money, what is right for me maybe not right for you and whatever you choose it will always be a compromise between safety and cost.