Here is my experience with the 'standard' contoured cases:
The older standard (IE: before they added that silly looking black strip to the top of the exterior pocket):
-This case will fit ANY tenor I own (LH, RH, or split bell keys), without any clearance issues.
The new standard (the cases with the black strip on the exterior pocket):
-This case fits very few of my tenors, regardless of what bell key configuration they have. It would not fit my VI tenor (the case didn't want to close willingly with the sax inside). The two that fit fairly well are my TT and Martin Indiana. And out of curiosity, I stuck a friends P. Mauriat in one day...oddly the case fit it perfectly.
Based on what I've seen, the old 'Standard' is the current XL, and the current 'Standard' is a bit smaller than the older versions.
So yes, an XL would likely fit much better. But it wouldn't hurt to find someone that owns one so you can double check how your horn fits.