So that translates to something like $1675 US. I'm of the mind that a great frame with a decent component group (which 105 is) is more worthwhile than a decent frame with a great component group.

You do have a wide range of bikes available at that pricepoint, so I encourage you to ride them all. You may not, as a newer rider, be able to distinguish which one fits you best (get a professional fit), but you will be able to tell how each frame rides differently from the others, and you will definitely fine ones that you like more. That said, if I equivalently liked a lesser frame with Ultegra at the same price, or was on the fence, I'd go for the Marinoni. 105 is great quality, enough so that one could race with it if they wanted. It's more that enough quality for an entry-level rider. And Marinoni frames are great by all accounts.