Interesting topic and quite coincidentally that you should post a thread on "Cross-Handed Putting!
I actually have been trying this "cross-handed" style of putting a couple of times recently but ... without much success tho' ( but even my conventional type of putting grip sucks big time ...hehehe!!!)... So I think I'll just stick to my earlier style of putting grip
Anyway!!! From my very very limited knowledge, I understand that not many, even the pros, are using this type of grip... Only a few and Jim Furyk is one of the few crossed-handed putter and he has won the US Open ( a major ) and several PGA titles ( then again come to think of it even Jim Furyk's swing is unorthodox
)... So I guess at the end of the day ..its personal ... its about what suits you ...