I second the recommendation of the Endura for price, durability and availability of a trainer. Also for SD purposes I would not worry about liner lock failures. The older non recessed AXIS locks were evidenced during our own force on force to be prone to failure using angle one cuts (traveling high right to low left) the most common initial cut. Here is something I did on the Subclaw. I have spoken to Boker and Chad about doing a trainer for the Subclaw.
MODERN COMBATIVE SYSTEMS - Boker Subclaw