Since money is your only criteria, you should switch. Then in a year and 1/2 to two years or so when Direct TV costs you more or they also want at least as much to upgrade you can move somewhere else. There are people who do that and apparently are happy doing so. Just to let you know there are some of us here who have been with Dish a long time and get many perks because of it, either equaling or even exceeding that $100. Sometimes it depends on what other discounts or promotions you have had recently, as well as how well payments are received, and your programming level. I have had the TOP250 or whatever the top package was at the time for somewhere around 13 years. Pay on time. I feel Dish has rewarded me for that on several occasions, most recently when they changed how you can get EuroNews.
My only point is, if you are willing to have a different carrier when the time comes to upgrade to newer technology you will indeed save some money as a new customer. I have found staying, I may pay for the upgrade, but get alot back in return for staying. I would rather do that then lose channels we watch that others don't carry, or don't have in HD. I might feel differently of course if Dish did not have want we want for programming, but that's a different decision than simply a money one.