www.savebeesflorida.com (Honeybee removals and top bar hives)
as a regular member of Biobes forum I will try to post few pointers about Phil's central entrance design;
Since bees place stores on both sides of the brood nest Phil rearange the stores before winter - moving all honey comb to one side of the nest.
That said, Phil is changing his design now to end-side-wall entrance with a periscope and a deep litter floor.
Phil's central holes design works extremely well in our wet cold swedish climate. Down to -27 C !
That said my own TBHs have only one top entrance hole which is 30 mm in diameter and is placed at the end of the side wall.
I have solid floors and windows on 2 hives only (not enough reused glass).
So far I tested periscope and top entrance with good results; colonies overwintered an exremly long and cold last winter.