This is a great question. I'm a bit reluctant to say that this is a good option, but also to say that it's not. I'll share with you the background of my thought process.
I've seen Wordpress sites that could reach far above your traffic with minimal resources, at minimal cost. I've also seen Wordpress sites that could barely function on high resource, high cost dedicated servers with a tiny fraction of your traffic. This is because every site tends to be built differently, and the real power behind it's performance goes to the choices of plugins and theme. Any combination of plugins and theme could set off a seemingly infinite number of reactions that cause each site to perform differently per visitor.
Generally speaking, if the site is well optimized and runs near to that of a base Wordpress install, I would prefer one 2GB server over two 1GB servers. The reason being that MySQL may need more than 1GB, but the website itself likely needs less at all times. It gives MySQL more room to burst.
Hope that helps at least some :)