If you entertain a lot, get the XL. My wife, who was totally against the BGE at first, forced me to get the XL, stating that if we were gonna get the $*%& thing, then I better be able to feed groups off when we entertain.
She was so right. I have the spare second DIY grid, and I still run out of space at times when cooking for a group. Plus, when cooking the larger cuts, it's just nice to have the real estate. Are there work arounds for the Large? Sure. But then the same work arounds would yield an even greater area to work with on an XL.
I've never regretted the extra $$$ for the XL, not for a second.