I used the HS system for several years. Magazine fit was always an issue. There were really tight and required a lot of pressure to lock into place, and of course required very deliberate action to remove once the release button was activated. Each mag had to be fit to a specific rifle and most would not work in another rifle.
The Badger M5 DBM system, as used by the USMC on the M40a3, is as close to bomb proof as you will find. The secret is in the use of the Accuracy International Chassis System magazines, which come as 5 or 10 rounders. Spare mags are readily available and cost less than the HS product.
Since Badger brought the M5 to market several years ago, a number of manufactures have jumped on board an now make similar products. Guess that is a testament to the theory and execution of Badger Ordnance.
What Steve said. I purchased mine from him and had GA Precision install it. It requires minor inletting of the stock and George is set up to do the job right.