I'm a RH player who has been putting left foot forward for a couple years now (after many more years with right foot forward).
It works better for me because of a couple things:
1) I practice it. A lot. As in almost every day, somewhere around 50+ putts from 15' and back. I've always been one to practice putting and I struggled along even using my old stance. The key here is I put in the time to adjust my body and mind to something that initially felt different but has become highly repeatable for me.
2) My hips and shoulders are forced to start and remain much more square to the basket, which helps me immensely in being on line (which used to be a massive problem for me).
3) For some reason, I am much less likely to put the disc on an inadvertent hyzer line. I now get nearly all putts coming out of my hand as intended (flat or, for longer putts, a slight anhyzer).
There you go - that's what works for me, but that doesn't mean it is anything other than one guy's opinion.
I truly believe the biggest keys are to find a delivery and practice it to make it repeatable. Don't practice it until you get it right, practice it until you can't get it wrong...says the guy who still gets it wrong at least 20% of the time despite nearly daily practice.