Pure acetylene is unstable. It is usually used while super saturated with LPG or other hydrocarbons. The popularity of acetylene was originally developed from the relative ease that it can be produced from calcium carbide, or lime stone and coal.

Propane is cheaper but also more limited on high temperature.

HGX is advertised to increase the flame temperature without the cost or instability of acetylene. MSDS Sheet reference is given.

http://www.energyadditives.com/products-services/cutting-fuel-additive-hgx-3/msds-sheet/

HGX is a mixture of petroleum distillates including naphtha with heavy aromatics, making HGX more of a health hazard than LPG.

Safety precautions and economics of each application must be considered.

Thank you sir for your answers..