The claim that bathtub liners cannot be chipped or gouged is not true. In fact, bathtub liners are eaisly scratched and if a sharp edge is dropped or scarped up against a bathtub liner, it will be damaged. This is also true with a refinished bathtub, but a refinished bathtub can be easily repaired.
A cheap or improperly installed bathtub liner can end up being a headache for you down the road. Bathtub liners tend to leak at the joints, or at the drains. When this happens water will accumulate between the liner and the bathtub causing mold, mildew and an odor to develop causing the liner to feel "mushy" when standing on it. Research has proven that mold spores inhaled, even in small amounts, can cause serious health problems.
When tub liners get to this point the only recourse is removal of the liner and disinfection of the tub which can very costly due to the nature of the installation process.
In most cases we can replace tub and tile for around the same cost of a quality tub liner and wall system.