Fsmithjack --
Latest reply of mine was with the intention to hone in more precisely on where you're coming from, so to help you get a bearing on how to more accurately answer your own initial question: are the JBL K2 S9900's potential speakers for you? Of course an audition prior to purchase would be the preferred solution, but being this is not your option as is there are other methods to appromximate a decision, as I tried to present them. You mayn't worry on these matters, but a bit of effort on your own part is necessitated to try and be a little wiser on your choice, I'd say. I certainly never meant to discourage you, on the contrary.
My blunt advice would be (if that's what you want): buy them.
Ohlala --
Whether 2 or 3-way seems irrelevant here. Essentially the S9900's are an augmented (with a super-tweeter) 2-way design, a design that can hold clear advantages compared to multi-way speakers in dealing essentially with one cross-over only. Perhaps the most obvious drawback to point out in this case, in theory, is having a 15" extend to roughly 900Hz, but having heard the midrange from these has only convinced me of its traits. Conversely a 15" with midrange capabilities on paper would suffer LF extension, but I'd go with the fleet-footed, tactile (/downright explosive) and nuanced bass quality from the S9900's over most any of the more typical hi-fi alternatives sporting smaller units, and in-room LF extension feels like they're able to reach ~30Hz quite easily. Which is to a say: focusing on ultimate LF-extension here seems a fruitless endeavor when overall bass quality is much more important within the spectrum most would ever care for.