Hi carey1110~
I thought I might chime in here...
I agree with most of the comments posted, especially with your own 'gut' responses that the XLF's will likely get you exactly what you're looking for.
Their physical presence and the ability to 'pressurize' that large, open space will be remarkable, although I believe every speaker system in your size room will benefit from a world class Subwoofer. If there were any way you could experience both models in the space at the same time (unlikely, of course) I don't believe there would be any doubt between the two. The larger XLF's~
I'm not one to get caught up in the latest technology when it comes to speakers and frankly, as capable as Daryl is, David was the catalyst and anything developed in his presence was as good as it could be at the price point. Don't worry about when they were built.
For my money, hands down, I think the space deserves a speaker the size and capability of the XLF.
For that matter, why not a Mint pair of the Alexandria's? (Shameless plug)
Best of luck in your search and when it's all said and sung... you will love whatever you end up with...
Best regards,
Jim
Jim Gray Designs
jimgraydesigns.com