Left-handed pianos do exist. I recall hearing once of one left-handed concert pianist who turned to such an instrument, and found it to be a complete revelation. I can't remember his name though, rather it is just something I recall seeing on the television, once.
So, sorry, I guess it's harder.
I'd be interested to know if, as a left-handed pianist, you find it easier to play certain pieces, such as Chopin's Op.10 No.12.