Harbeth 40.3xd vs Graham LS5/5

Haven't heard, but interested in what responses you get.
I'm drawn to the looks of those slotted apertures on the LS5/5 and wonder if the theory behind them works(?).
Though I'm not in the market for another speaker the LS5/5 is weirdly desirable to me as an historical curio alone. 

op

the harbeth mon 40 series has always had a forward (but excellently detailed and nuanced) midrange... it is characteristic of that speaker, despite it huge size and excellent capability also in the treble and bass regions

@tobes

you can search bbc ls5/5, there is plenty written about the bbc speaker development program that created the various models... see link below for the seminal white paper written on the ls5/5 design... the cabinet slit is to manage horizontal directivity, but like any other design choice, it comes with tradeoffs (sec 4.1)

http://downloads.bbc.co.uk/rd/pubs/reports/1967-57.pdf

the nearest relative to the ls5/5 is the modern spendor sp100/classic 100 series

@jjss49 i have indeed read the seminal papers and understand the concept of the slots.
my question really is posed to someone who has heard both the speakers.