I also pronounce Slough all three ways -- Despond and the town are the same, the pond/ditch/bogs at home are slews, and exfoliation-related things are sluff. Most of my other pronunciations are US Murcan, though, and mostly coastal California. I would still have understood any of the pronunciations.

Some of my faves are Off-en Of-ten, Sa-mon Sall-mon, Los An-jel-es Los An-gle-ees (which is a clear indicator that an anglo person was raised in LA in the first half of the last century), spe-shul-ty spe-see-AL-i-ty ...