Yeh I have a big tool too
.................had it for nearly 40 years........always assumed it was the official approved Lotus tool with combined LH RH thread at each end and made from a solid piece.
I must have removed over 100 hubs over the years with it and never had to use heat. Once some pressure has been applied even worse case only had to tap the end of the bolt head.
One thing I have always done though is loosen the nyloc hub nut till flush with the hub end and place a 3mm metal circular disc over the end of the stub shaft and nut that the tools centre bolt then presses against. This prevents any risk of swelling the the threaded end of the hub shaft if a lot of force has to be used and when the hub does break free a large lump of metal ending up in your lap.
I assume the small groove on the outside of stuglimours is the standard identifying mark seen often on LH threaded nuts as mine does not have this groove.
Regards
Steve