Burning a qt in 3000m isn't bad - leaking it is substantial, and messy.
As to synthetics leaking more: right or wrong, theories, science, arguments, etc. notwithstanding...
I have found in a lifetime of auto repair that yes, you will occasionaly get an increased, or new leak, when changing to synthetic oil. I've seen seal leakage start, valve cover gaskets and side cover gaskets squish out, and seepage from every sealed orfice/gasket, when there wasn't a problem before. I've seen the same type of things when Slick 50, or any number of the newer additives are used, as well.
I use synthetic oil in my personal cars,BTW. I'm just saying this is the way it is, and I have a lot of miles in the business.