I don't understand your question. Why would it be installed incorrectly? That is on the contractor, who should be aware of every selection you are making, and the specs, and should be competent. His subs, plumber and tile person.... should also be competent and aware of all proper prep for installation of anything! Post a photo of the "bench" that is your concern. Mildew is a function of moisture, not whether something is acrylic or porcelain. Adequate ventilation removes moisture.

You can not use a drop in tub with a tub/shower installation, despite many pictures showing that being incorrectly done. You need an alcove tub with an integral tile flange so that proper waterproofing can overlap the flange and direct overspray back into the tub. A drop in tub used as a tub shower will leak, and have yucky moldy water sitting on the deck, and running out onto the floor.

You need a designer with a clue. And who uses a competent GC.

You are not doing a ''refresh''. You are doing a a complete 15-20K gut to the studs job renovation. You are replacing all of everything. A refresh is paint the vanity, get a new towel bar, and a new light.

I saw that. But, never used by the OP doesn't mean it wont be used by a guest or future owner. Perhaps it would make much more sense to reconfigure the master for how it's actually used than to put money into such an extensive and poorly designed redo of a secondary bath.

Thanks for your remarks. Perhaps I didn't state my concern correctly.

RE: Installation: I have read many comments on the Kohler Archer tub squeaking. Some of the stories are on Houzz/Garden Web. That is my main concern. As for keeping the shower over the tub, resale is my concern.

As professionals have been kind enough to answer my question, perhaps one of you know of tub manufacturers who round the end of the tub for more comfort. The tubs whose ends are squared are not comfortable to me.

Thank you.