This is a great question. In short, I don't think you or your wife needs to worry about the cooling features making you guys feel cold in the winter. There are a few reasons for this.

First, most mattress "cooling" features today (such as the ones in the Posturepedic Plus) don't necessarily make the mattress sleep cold per se -- they just make the mattress cooler than it would have been without that feature. Materials like dense memory foam have many benefits, including comfort, conformance, and pressure relief, but can come at the expense of trapping heat closer to your body. As such, the cooling features that are added to a mattress like this help to offset that effect. Features such as PCM and PE fibers are most effective when you first lie down in bed and are falling asleep.

In addition, the vast majority of cooling features in today's mattresses are 'passive' cooling, not 'active' cooling. This means that they are helping heat move away from your body more effectively to prevent it from building up and creating the sensation of warmth, but they are not actively making the bed feel colder. Think of it as the difference between opening the windows of your car vs turning on the A/C. Turning on the A/C (active cooling), and could make the car feel colder than the ambient temperature outside, but opening the windows (passive cooling) can not. In the same way, over the course of a night, the maximum effect that passive cooling features can have in a mattress is to make it feel the same as the ambient temperature in the room.

I hope that's helpful.