Distinction between L1 and EB1-C

Hi All,

I live in Ireland and I've recently been offered by my company, a US multinational bank, to move to their Operations Centre in Florida as a Manager. I haven't decided yet if I'm going to accept their offer, so I couldn't ask further details on the type of Visa they'll be applying for me and my wife. At the same time I'm trying to gather as much information as I can, to be ready if I'll have the chance to negotiate my relocation package.

I had no idea what jungle of information is available by googling "US Visa", and after asking some colleagues who were transferred I realized that it's quite likely that my company will apply for a blanket or regular L1 visa. As far as I understood they are non-immigrant visas. Do I better off ask for an EB1-C? Or do I need to stay for a while with the L1 visa before asking my company to apply for an EB1-C?

Any help is much appreciated.