Amerilite has a replaceable bulb. You start with white and then you can use one of the many replacement bulb options, like the J&J Colorsplash or ones available at Florida Sunseeker. When those bulbs go bad, and they will, you can go back to white or get a new LED color bulb without changing the entire fixture.
When installing a new light, for the last at least 10 years, I would remove the incandescent bulb and install a white, or color-changing, LED along with a silicone (basically lifetime) gasket, depending on the customer's wants. If you use the light frequently, just changing the bulb to one of the white LED bulbs available will more than pay for it self in energy savings. It also keeps the light fixture from "cooking" itself. You might be surprised how hot a 300 - 500w bulb gets, even in a pool light surrounded by water.
You would need to find an installer willing to make the changeover.