I would not be comfortable with either. I would only use a tub with an integral tile flange in a tub/shower situation. I've never known an integral tile flange tub (when installed properly) to have moisture damage, while it's all too common for drop in tubs used as tub/showers to have moisture issues behind the wall. Even the ones that people think are installed "correctly" (ones with aftermarket kits) will eventually have the seal fail and water will infiltrate. It's only a matter of when, not if.

If the tub is acrylic you can put on an applied flange. The ABS plastic strip is clamped to the sides you need and you use acetone to chemically melt the two together. The little groove left at the top is then filled in with silicone. You will not have any problems.

If your tub is castiron, I have no idea. Personally, if it is a clawfoot tub castiron is fine, but if you are going to do a 3 wall alcove I wish you the best of luck. Oh, reinforce your floor if it is on the second floor. :-)

It's a cast-iron drop in flanked by a wall on two sides. How would a clawfoot be better - because of the continuous curtain? I'm sufficiently alarmed about proceeding on this path, but I have been unable to find a tub with an integral flange that is 48" long max. Any suggestions??

Lovely! This is just the problem I have. Before I ordered my expensive cast iron jetted tub, I contacted Kohler. Kohler reps stated my cast iron tub could be used in a 3 sided alcove. They even have a pic of it installed in a 3 wall alcove as a shower tub combo, on their website. The tile lip/flange they sent is rubber with a ridge that fits between the backer board edge and top of the tub, held down with a putty. Had I known this was going to be so messy and undesirable I would have never bought the tub. I have been dissappointed with Kohler's lack of into on their products and recommendations that are unrealistic. I already had this tub installed long with my installation of expensive glass tiles as the surround. I will now have to worry about leaks at the rubber inserted flange.

I picked the tub based on its use as a 3 wall alcove. Had I ordered quartz or some kind of deck over the tub, perhaps this problem would not be so apparent. I do realize that I will now not use this as a shower and use the hand held sprayer as a tub rinse spray rather than a shower.