In the interest of this "review", I will point out a point commonly not understood by those new to BU:
BU follows the longest chain.
BU does not always follow the longest chain. In general BU operates in the same way as in Core, BU nodes follow the longest valid chain. There is a slight difference with respect to the blocksize issue. It is possible BU nodes will follow the longest chain, where the blocksizes are arbitrarily large, but only under certain limited unusual conditions. There is an “N depth” idea in BU, where nodes switch from regarding one chain as valid to another chain, if the chain with larger blocks has a lead of N blocks. The default value of N is 4 and N could be manually set to any number, including infinity, when BU nodes will never switch to the longest chain. Only if N is manually changed to 1, does BU follow the longest chain with respect to any blocksize. Therefore the claim that BU always follows the longest chain is false.
It is not false with respect to any setting other than infinity (but your point is valid since infinity is a apparently a valid setting). There is never a guarantee that any Bitcoin node will converge to the longest chain in finite time, only eventually. The exact same guarantee applies to BU, though it may take longer to agree on a chain than other implementations.