If you live in the UK then Maxton is a no-brainer. But as good as they are, the fact Maxton will only do a complete changeover service makes it an impractical choice from this side of the world. Shipping an entire set of forks each way becomes quite expensive.
I got them to do the forks for the SLC and I was able to source a set of (Japanese) donor forks from UK ebay for au$50 delivered to their door, plus the AUD was at 64p not <50 and it still cost quite a few bob once they got the full works done to them.
Racetech emulators seem like a great idea that never got fully worked through. You have to buy a bunch of bodgy adapters which only do half a job, and if you're not capable you need to pay someone to fit them and modify the other innards.
These things claim to be a drop in fit to completely replace the other internals, apparently properly made to exactly suit the particular fork. They seem to address most of the shortcomings of the one-size-fits-all racetech bits, including a piston ring to prevent external leakage, and adjustability without having to remove them.
While the end result may be no better or worse than either a very well customised Racetech setup or a Maxton conversion, they seem like a good value drop in product to me. My 'Max-Patina' 79 Jota is in line for some upgrades, I might give them a try.