MR day pack lid will work on the DT bag- just need a female buckle on the strap coming up from the DT bag. The regular MR female buckles will thread through the DT bag's back lid strap. I know I can put a MR Glacier top lid ( same as a Nice frame daypack lid, but slightly smaller) on the Kifaru LH bags. And I can vice-versa also put a the Kifaru standard lid on the MR Glacier pack.
I know it works fine on the Kifaru LH bags and the DT bags, since they all have the strap coming up from the back of the bag to attach to the Kifaru lids. The MR lids have a male buckle coming out the back of the lid and all you need is a female buckle on the Kifaru bag lid strap and it will work fine. Just need to use compatible colored hardware - ( all the tan and foliage buckles are inter-changeable, but black only works with black).
BTW- Regarding the XTL price; I believe the $96 dollar price you stated above for the XTL lid is only the additional added price to the Timberline, or DT bags if you order the XTL lid with the bag instead of the standard lid. I believe if you order the XTL lid either as either an accessory or in addition to the standard lid, then the XTL price is $116. I could be mistaken about that, but I think that is the case.