Pressure reduction of medium to low pressure saturated steam will always result in the steam superheating to a small degree.
Unless your pressure reduction is great, the superheat should not be so bad so as to be a problem.
This is not an issue related to the type of gate valve that you use, but it is related to the laws of thermodynamics.
If having no superheat is absolutely critical to your process, then you should consider a steam conditioning valve that reduces the pressure and desuperheats it in the same valve body.
Even at that, most desuperheaters can't control right at saturation and have to control 5-10-20°F of superheat.
I have used plenty of self contained regulators to pressure reduce saturated steam, and would not hesitate to do so again.

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