I had a similar situation buying the PDG's EVO sibling sight unseen, after having used the TLT6's TLT5 predecessor.
In the TLT5, I had the 26.0/26.5 (same shell and liner, just thicker throwaway footbed in the "smaller" half size).
In the EVO, I bought the 25.5/26.0 (ditto on the fictional half size).
Two of my buddies who did the same thing couldn't sense any difference in interior length despite the 8mm shorter bsl.
But given that I was close to maxing out the interior length on the TLT5, I could definite...