Sorry no, but I was glad to find this thread as it's exactly what I'm having to deal with now. I removed a cast-iron tub and have to put in a new one, but cringe at the thought of installing another 350 lb tub.
The cast-iron tub that I removed had a dull, stained finish after 22 years. I would have thought that with all the hubbub about durability of cast-iron that this thing would last much longer still looking good. I don't see the point of dealing with all that weight if the finish is not going to hold up anyway. I guess the stability and sound dampening is a good reason to buy one. I'm still open to considering cast iron if I can be convinced that it's worth its weight. Maybe I just had a cheap one with a mediocre finish. I'm going to look into the Americast that was mentioned earlier.
One note about thinset under tubs. I used Custom Speedset to embed a neo-angle shower base. the base was spongy and flexed when I stood on it prior to the installation. It's really nice and solid now in the thinset. Speedset is a fast drying thinset that is kind of spooky to use for regular tiling since it dries so fast. But, it worked great for this application where it's beneficial for it to dry quickly. Also thinset isn't really supposed to be applied in thick pours
like for this application. So, I'm surprised that it's specified to be used for shower and tub installs. That's another reason I went w/ speedset though.