I'm just a tad late to the party here but I have to say that, at this point you know you're style, you know your strengths, and you can grow whatever beard you want. So, if a solo mustache is something you want to try, more power to you! If you don't like it, so what, you'll have a great full beard or goatee again soon enough.

By the way, the circle beard looks great, so why are you even considering this?

Cheers!
Tom


Some helpful links:
Library Central of Beard Growing


Taming the Wild Mustache
Tips for eating and drinking with a big mustache

Excess on occasion is exhilarating. It prevents moderation from acquiring the deadening effect of a habit. ~ W. Somerset Maugham
A jerk with a beard is just a bearded jerk, but a bearded gentleman is awesomeness personified. ~ Triibeard