Meself - C/C# keys are also made of plastic, with a spring-back system that seems to break all too quickly (hence, I prefer a bit of a pinky-stretch for the model we both have).

"They don't play the extreme upper register easily, and in particular the high A can be unresponsive." (Jack)...the highest note in my repertoire of English hymns and folk-songs is high G, but, in agreement, when I go through the chromatic-scale it's the high A I struggle the most with. However, I find low C# easier, and use it in the hymn "O Jesus I have Promised", and my own folk-song "Fondly and Vividly".