LEL is 7-12 August, so it is either/ or.
Completely different experiences in terms of number of riders and scenery, of course, though memorable support on both brevets. I've only ridden 1 x HBKH vs. 3 x LEL.
For those who worry about such things, HBKH has not been homologated by LRM in the past, despite following their rules, and AUK had problems recognising AUKs riding the event. HK and I greatly enjoyed the event regardless of AUK's issues and I would be happy to ride it again.