Can I replace a built in shower valve with an exposed?

I have a Triton Domina HP thermostatic mixer built in valve that has broked (snapped at the controls) and I need to replace it. I can not replace like for like as they no longer manufacture this animal. Is it possible to replace with an exposed valve and are there any advantages to having an exposed valve? As an aside, they all seem blooming expensive for a cheapo bit of plasctic.