...it was a newb question. 
It seems a shame that Cartier did not do a larger production of the time-only Tank XL. As you say, it is a nice option to have and for the non-elite collector it would appear to be quite difficult to own one.
Related to that, it also seems a shame that the only XL now available will be the one with date & power reserve complication. While the watch is extremely handsome, as I can attest from having seen it in the metal, there is something to be said for a time-only tank in the larger case and as a non-special edition watch. Maybe it will resurface down the road & perhaps in good old Yellow Gold? I would certainly save for that. 
Just MHO and thanks again for the clarification.
Best regards,
Tom
P.S. Fantastic pictures--particularly love the two-shot of the standard and XL Tanks--really terrific!