ELAC - thanks for a comprehensive post. You appear to have missed "NOD's" reply where he corrected my post, but I appreciate your pointing it out again. It does show the degredation of stopping distance with defective reversers on a poor surface. He deduced a 31.5% increase. I have used 'icy' figures as those are the only ones that I have been given here for the AB on degraded surfaces, whereas I have access to the 73 figures which have a whole range of penalties from good to icy.
Personally, looking at the 'history' of the new runway surface in CGH and other 'new' surfaces I believe it was indeed 'poor', as I think the day's previous landing of this hull and the ATR showed, and I remain firmly unconvinced that a 55m increase in LDR was appropriate. Although the term 'slippery' is, indeed as you say unquantified, in the MELs I am acquainted with it is sufficient to preclude landing with a u/s reverser.
Operations on slippery runways or runways contaminated by snow, slush or standing water are PROHIBITED.
(737-700)
The addition for u/s reverser/s come from the 737 performance manual (not MEL) and as I stated the use of reverse WAS "considered in the original calculation of RLD for this aircraft". The point I was trying to make, rather than throw loads of % figures around, is that if there is poor or little braking action then reversers are all you have until you can get the wheels to grip - negligible or not.
The reverse handling techniques you quote are pretty much universal for wing-mounted engines
While you are there, what EPR would you expect to see using max reverse on a 320? 1.02?