I have a T5-T3 connection on December 29th. I was contemplating whether to go landside and take the scenic route or take the airside bus from the connections centre bus.
While using the HEX for transferring landside is possible, it may be crowded. I’ll probably take the airside transfer bus to T3, although I haven't yet decided whether to go landside there and use landside fast track security or go through transfer security and hope fast track operates.