My daily commuter bike is equipped with a Sachs/SRAM Spectro 7 IGH with coaster brake. It has been used for the past 7 years of all weather (rain, snow, road salt, -4°F to 100°), daily commuting for approx. 35,000 miles. It still works fine and always has no matter what. It was original equipment on the department store city bike I bought new in Germany for approx $135. The bike still works fine too.
No experience with a Shimano 8 speed but I have a Shimano 7 speed IGH on a cruise bike and it is OK but the shifting gets sticky in below freezing temperatures