Mine is still running the stock XHP35 HI. I have several other throwers but occasionally consider a swap for the TN42. Have you seen the TN42 V2 with the SBT90.2? It’s $300 but Amazon currently has a coupon for $69 off. 
I bought the drivers from Lexel, a longtime BLF member with extensive driver building knowledge. He designed lots of different drivers for upgrading existing lights and contributed to driver design of production lights, too. Unfortunately he is MIA, and we’re all hoping he will come back to BLF sometime.
There may be other options, such as from Texas_Ace, another well-respected member. See this thread for more details.
I sold it because I have several other throwers of similar size with similar performance. I really like the size and look, but just didn’t end up using it. Sometimes I think about buying another one, but only if I could swap the driver to run Andúril. 