I read this thread from beginning to end and i think people needs to know few things about professional refinishing.
Bathtub refinishing is not for everybody...
if you have few thousands of dollars available and few days available, you definitely should choose to replace the damaged tub (no questions about that). there's nothing like new tub & tiles & plumbing.
Bathtub refinishing solution exists to help people that has a damaged tub but don't have the money or the time to demolish and replace the tub & tiles.
Bathtub refinishing (when it's done right) is a great solution to extend the life of your fixtures.
Bathtub reglazing finish is not bullet proof!!!
Professional coating for tubs is basically a polymer that was designed to strongly adhere to the surface (after a proper prep) and it is high gloss and has certain impact resistancy. the finish is designed for impact of human body and light solid (shampoo bottles soaps etc.)
BTW, heavy shampoo bottle dropped on a tub from high can chip a real porcelain tub !!!!! so there's no reason that the refinishing finish would be different.
Reglazing should be applied ONLY by HVLP spray system. that's the only way to get smooth finish. beware of refinishes that offers brush or roller application. it might be strong enough but it doesn't look good.
In order to keep the finish integrity , refinished bathtub should be maintained like a standard acrylic tub.No abrasives , no acids , and no scrubbing pads can be used - only mild cleaners and a sponge.
NOTE: most people dont know that , but if you clean an acrylic tub with abrasive pad or abrasive cleaner you void your warranty.
so its the same with bathtub refinishing.
its very easy to maintain , and if you used a company that preps the tub right and use a good quality coating, you can have your tub in good condition for the next 5-10 years.
in case of such a rust on the drain:
the easy and expensive solution is to replace everything of course.
But you can get it repaired by a refinishing pro that should do the following:
1. clean the surface and degrease it
2. grind the rust completely with rotary tools
3. etch the surface using hydrofluoric acid
4. sand and clean again.
5. fill and even the surface with water resistant filler.
6. re-glaze the tub with professional coating.
Bathtub refinishing is a great solution to give face lift for a bathroom, while minimizing the costs. the results are amazing when it's done by a professional.
I personally have hundreds of happy customers with almost no complains.
I'll be happy to answer any questions about bathtub refinishing.
I'm not from the states, but my coating supplier is American and it's almost the same kind of market here in Canada.
i hope it was helpful.