LNF rates - Are any changes possible?
 

I'm holding a res with an approved LNF reduced rate for a 4 night stay.

Can I shorten my stay to 3 nights without jeopardizing the LNF rate or do any changes force a reprice and new rate change?

You should be able to check-out early once you are at the hotel. If you want to arrive one day later you have to make a new claim.

I've shortened a reservation by emailing Customer Care and asking them to do it for me. It has never been a problem.

The property management may allow you to do this. When I had a canceled flight, I was able to do this. If doing this for convenience, I think they are likely to be more willing to give you the later arrival data at the same rate if the rate the LNF was based on was one that did not require the longer stay. As far as I know, only the property itself (at their discretion) can make any changes to this type of reservation and maintain your discounted rate.

In my experience, CC has been unwilling to change the duration of a LNF reservation.

I usually try and get another LNF for the shorter/longer period and then cancel the old one (just did this for Chicago March 2010).

If only I could ;)

Sadly the LNF opportunities for the LAX Marriott seem to have dried up. :(