I just got an EliteFTS single prong retro belt and I was debating between the EFS and the Inzer, too. It seems that one of the big selling points for the lever is that you can get it tighter than a normal belt. For me this was not very important because I don't like my belt super tight.
My EFS belt was just a bit too big for me, so I had to send it back for the next lower size. However, it was beautifully made, very supportive, yet pretty flexible, too. It took a solid three weeks for me to get the belt from EFS because they are made to order. Inzer has some belts in stock, so they can get you something faster. EFS has an excellent reputation for customer service, although Inzer might be good, too.