You'll never get BC good on proper rough B roads, I spent months and few hundred on varying spring rates, tender/main setups and while it good at lot of things real rough roads still showed it's downfall.
I'm super fussy on suspension and fitted and owned pretty much all the brands offerings on an R and I can tell you without a doubt any of the short stroke coilovers are poor choice for rough road use .
4 and 3 with tender springs makes BC better on rough road but the main issue of compression travel and droop is real issue as you simply not got the strut stroke to cope with real rough roads, the stroke on BC need be doubled at the least for rough B road driving .
Other issue is valving it pretty slow in function, I've used ohlins and proflex and you can run way stiffer springs yet ride less crashy and rough road surface better controlled because the valving precise and fast in action .
People who say they pretty good probably forgot what good is or roads not bad enough realise the limits .
It not just an R issue but the R's poor handling really does want suspension done well.
Bilstein inserts or long stroke coilovers with 75mm id coils will cost 300 to 400 gbp a corner roughly, difference is night and day .
Best experience so far is bilstein if using on roads a lot, off shelf ohlins japan good, JIC not bad, dms and custom springs, Leda not worst coilover but expensive for what get and similar money can get way better in custom effort .
Original new struts and custom coils with slightly increased rates and dropped max of 20mm also very good rough fast road .
Suspension very personal thing but if review a taiwan coilover stroke range the issue is undeniable for why is potential issue for many on rough road daily driving .
Will agree with Johnny that many far from best as rates/preloads/corner weights, and general geometry all off but biggest error is generally wrong choice of suspension for intended use through poor choice and poor product details .