There certainly is nothing wrong with Fatar keybeds. I'm sure just like any mfg. they make lower end ones...Kurzweil has used the Fatar for many years with outstanding results.

They build many different models, both synth action and Hammer action.
Certainly some PSR's I have tried through the years had what I would call spongy keybeds....along wth other mfg too.

I do like the T4 better than PSR910