Butel is best if you want to buy a software package for each of your scanners. Several other packages service multiple scanners, this is especially useful if you like to keep your sanity and load the frequencies/talkgroups the same in each scanner.
Great news, as I have both ARC780, and ARC250PRO registered, but had not used them since switching to GRE products. I upgraded both today, and will fire them up!