Anyway, tile is too heavy, less tolerant of flexing, and requires extra labor and maintenance. But then, I generally lean to function over form.
Have to disagree with most of that.... Weight is minor, when compared to the rest of the conversion. Hardibacker is something like 2 lbs per sq ft. Tile and grout don't add that much more.
Labor for installation can be just as simple or as complex as you desire and when compared to cutting and fitting a prefab fiberglass unit, it might be easier to custom fab than to fit. As stated above, you can build it to fit whatever space you need it to fit. Maintenance is also no more than a fiberglass unit, if properly installed.
I installed Italian glass mosaic tiles in our custom shower enclosure. Been working great for 4 years now, and probably close to 30K miles. No maintenance necessary and it looks so much better than a prefab unit. Now if I can only get the rest of the interior to look as nice as the shower.
I would do it that way again, in a heartbeat!