Acrylic vs cast iron bath tubs- which is easier maintenance?

[Amit M.]

So far I have only installed Kohler Villager cast iron tubs. They are cast iron, low rise (14" height) tubs that have been fine regarding durability. My tenants tend to be higher end professionals, so my units don't get much abuse. 

For my current remodel I'm thinking of getting an American Standard acrylic tub that is deeper, looks nice and is better for soaking in (the Kohler is too low to soak in.). Plus it's cheaper. 

I'm having a hard time determining which option will be more durable from a maintenance perspective. From what I have read, cast iron is very solid, and the strong enamel finish holds up well. But I'm told if it gets chipped, it's expensive/hard to fix nicely. The acrylic cannot take abrasive cleaners (will tenants know that?), but cleans well otherwise. And I hear it's easy to fix scratches (fine sandpaper) and to buff it if the finish dulls?  Is that true?

Anyone with experience maintaining cast iron and acrylic tubs- I'd appreciate your perspective based on your experience. Thanks!