If ordering a new PC, you can request the factory install the type of window you want there. If buying a used PC, make sure what you want will fit in the opening before buying it.
We have the old style sliding windows in our 2350. They are real good for flow-thru ventilation, but easily broken into if left unlocked. The current-day top-hung windows don't allow for nearly as much air on their own, but turn on the Fantastic fan to the lowest setting, and you get a lot of air. The top-hung windows are much better for rain protection when open and you can't crawl through them either. They also are better for exceptionally windy days to control the gusts better. Also when open, they don't allow direct sunlight in on warmer days, so the interior stays a little cooler.
With our old sliders, we have a pull-down awning on the driver side dinette window to protect it when open while raining. On the passenger side we can open the main awning a foot or more to protect our open slider windows on that side, so we have a way to work our sliders just fine. But I personally prefer the current-day top-hung windows for the reasons I mentioned. Oh, they just look nicer too.
I do understand your concern. I have to admit, it is nice to sleep with our slider wide open when the conditions are right. It can feel as though we are sleeping outside.