I guess I'm about a 4? I'm more poly overall, but it also depends on the situation, and the person / people. Every relationship is a different experience. It doesn't come naturally to me to be completely monogamous for years at a time, but I can do it if there are other aspects of the relationship that make this kind of sacrifice seem worthwhile (all long-term relationships involve some sacrifice after all). My usual style in a new primary relationship is to be monogamous at first and then transition to poly after our relationship has a strong enough foundation. How long the mono time lasts depends on the person I'm with and, often, how poly-inclined they are. It's important to me to have some mono time at the beginning of a relationship so we can just focus on each other, but then I like to relax and trust that we love each other enough that our love won't be threatened by having other loves or interests in our lives.
I also don't know where I belong on the poly - swinger spectrum. If I understand correctly, poly = having multiple loves, whereas swinging = having multiple sexual partners but not loving more than 1 person? My natural tendency is to have a primary relationship but be free to pursue secondary love interests and sexual interests. So maybe I'm poly and a swinger? What about the gray areas like loving someone as a friend, and enjoying having sex with them, but not feeling romantic love for them?