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.

Looking at the graphs in the BBC paper there doesn't appear to be any advantage to using the slot for the bass driver when utilised in the 3-way design(?).
Hard to tell from the graphs if there is much advantage to using the mid-slot either. 
Anyway I suppose the proof is in the listening.
Looks like Graham must have done away with the 4db bass boost via preamp EQ with their iteration.
The design does look very retro-cool though.
Will be interested to hear of any comparisons to the M40.