Mercedes' system is far superior - annoyingly! Their ASS works out where the piston's are in their stroke and simply fires them with a quick turn from the starter to get it going.
To be honest, I think all the systems are floored because they use the starter motor, and the starter motor is old technology! It's slow, noisy, rough and really needs to be binned in the favour of something more advanced!
I know a company called CPT - Controlled Power Technologies who offer a product called SpeedStart®.
You can see the interesting technical bumf
here on CPT's website, but in essence, it's an electric motor which starts the engine very quickly and very quietly. And most importantly, it reacts very quickly to driver request on reboot.