Has anyone had any success changing a points reservation to different days when when redemption rates have now gone up? I made my reservation prior to devlaulation and now need to shift my dates. I am pretty sure I am SOOL but i figured I would ask the experts.

I don't think you can. That's the cost of being able to rebook at lower rates when they drop.

It depends on the property. Sometimes you end up paying less, sometimes more.

If you change a Marriott Bonvoy Points reservation, it will reprice to the number of points required at the time you change it. Could be higher. Could be lower.

This applies not only when changing the dates, but also when changing the number of guests, switching from points to certificates, and any other substantive change. It even applies if you change nothing except to accept a new rate (using "View/Modify") -- which is a good thing if the rate has gone down and something you wouldn't do if the rate has gone up.

A few updates to your reservation do not change the number points. You can apply an SNA or update the "Any special requests or needs?" field under "Choose Room Features" without repricing the number of points.

I'm often forced to click on View/Modify to see details of my reservation, such as room category and cancellation deadline. Are you saying that I risk having the rate change (not in my favor) every time I do this? OTOH, at times I've been convinced that there was a change to the cancellation deadline after the reservation was made, so I'm always nervous when I don't have an email confirmation that lists all these details clearly and ideally shows me the text of my special requests.

The view/modify will only bring you to the view screen. You actually have to click the edit button, search for the room, and accept the changes to change anything - but it is a great way to change for a lower price if the price was reduced without rebooking a new reservation.

How bad is the points difference.

And no, Marriott call center associates cannot, nor can properties, reduce the point cost of a night. No matter how much you complain, ask for managers, no one can change the cost of the nights. It's done by a computer. The people that can change those things are in India...and no one can get them on the phone. So, save yourself the time and frustration, re-run the rates OUTSIDE of your reservation, see if it's a change you're willing to accept, if so, then actually do it. Otherwise...it is what it is.