Peter - the MN straps are very good, but as far as I know they don't work with fixed springbars (as the Gen 1 has), you can't fit the hardware through the space between the case and springbar. Normally to fit you remove the springbar, insert the strap into position, then refit the springbar.
If I'm wrong, I'd be very happy to know as I have the Gen 1 and 2 and I don't like Nato straps - with the fold back and double metal retainer.

If I'm wrong, I'd be very happy to know as I have the Gen 1 and 2 and I don't like Nato straps - with the fold back and double metal retainer.