So.... I spent the evening searching for batteries and have purchased the following for some 'Battery Rolling' and spares in the C9.
Samsung 30Q 18650 3000mAh 20A 3.6V/4.2V IMR High Drain Battery
LG HG2 Brown 18650 3000mAh 20A 3.6V/4.2V INR High Drain Battery
Efest 18650 3000mAh 35A 3.6V/3.7V IMR High Drain Battery
All Flat Top and unprotected.