I use NF as well, though now it is mainly for the streaming because my NF experience used to go something like this.
I am in the mood to watch movie "A" ,well movies "D" and "E" showed up today because "A" still had a wait. Oh well I will have to wait a few days or weeks for "A" to show up. I can either watch "D" and/or "E" and send it back so "A" shows up or I can let them set on the counter and run to BB to get a movie I am in the mood to watch.
If I had to wait for movie "A" it wasn't that big of a deal but my only backup was the other discs that I had gotten from NF and either they were movies my wife wanted or I just didn't want to watch them right then. With Vudu I have most of the movies I want to watch at my fingertips. If for some reason I can't rent a movie I really want to see because of the VOD window I still have other options right at my fingertips.
I now only purchase BD that I find I will watch again and again. I also rent the ocassional BD for the "theater AQ". Those, however, are getting fewer and fewer. The Vudu HDX/HD is a great blending of quality and convenience that make it worth every penny. I could go back to the 20 bucks a month NF plan and watch the movies I want somewhere around the time that I want to watch them, but paying as I go for movies that I want to watch when I want without having to get my lazy butt up out of the chair is priceless.
An example of a Vudu plus is... the other day I had some friends over who have kids, I do not, so while the adults were conversing the kids wanted to watch a couple of movies I turned on the filters and explored Vudu for 3 star and above rated G family movies and came up with a list for the kids to choose from. They narrowed it down to two and away they went the first being Horton Hears a Who. What I am getting at is there was no need to run out to BB, no searching through my collection to find something they would like, just click click scroll click. That is something that 20.00 a month can't do.
"People are just as happy as they make up their minds to be."
--- Abraham Lincoln