As for the locked brummel vs the regular brummel or plain bury for strength - I'll take Brion Toss's word on that. He writes of Locked Brummel:
I don't think the regular Brummel or plain bury is going to improve on that. Also, the regular Brummel is far from secure.Properly done, this splice will approach 100% efficiency in strength and security.
Also, I have experienced times when stitching a splice is simply not feasible due to lack of needle and/or thread. But doing a locked Brummel was feasible since the splicing tool was readily at hand.