I have seen the Sterling Accord tub surround at Lowes that is very strong and durable. However, I don't want to rip out my existing tub. It seems that the Sterling products (Sterling Accord, Sterling Ensamble, etc) work as a kit with tongue and groove like system.
Does anyone have experience with using only the Sterling wall system without using their tub as well?
Most tub surrounds will work, as long as they are properly installed. The main factor should be where the surround meets the tub edge, to eliminate any leaking to get behind it. This is where mold would grow and water can wick into the walls.
If you have never made a mistake, you haven't done much.
Call the manufacturer.
Will the surround line up with your existing tub?
I had one manufacturer tell me their surround could be used only with their tub - they wouldn't allow you to file down the "tongue" part of the surround if your tub didn't have grooves in the right place. They said it would void the warranty (if you don't care about that, then go ahead). They also said the edge of the surround needed to line up with the existing tub.
The tub surround I got (which matches with the tub) is quite fragile & the manufacturer (Swan) provides inadequate packaging. If you do go with the surround, be very careful transporting it and installing it. I personally will never use the heavier plastic surrounds again - I will either tile or use the cheaper, thinner plastic ones. HD sent me 3 damaged shower surrounds (each additional shipment taking 2-3 weeks) - given the packaging, it wasn't surprising this happened (HD should be requiring better packaging from suppliers).