I can now say I have had a Bacon Sundae from Burger King.
I had kind of dreaded trying it not sure how it would be (just like you are thinking), but it was actually a pleasant surprise! Think Salty-Sweet. The taste of the softserve icecream, caramel and hot fudge overpowered most of what you tasted, but every so subtle you could taste the salty pieces of bacon.
Would I eat it again? Sure. At 510 calories-you can also add on an hour on the eliptical! (That's what I did when I got home yesterday!)
Thanks to Brad, Brett and intern Alexandra for trying it with me.