I think Samsung changes too much to the stock android experience, by adding a lot of strange features that nobody use, so I am planning to move away from Samsung to another manufacturer, and as you may know by now, I will switch to Sony, and buy the Xperia Z Ultra, a huge 6.44-inch phablet, my first phablet.
Personally I don't like what Samsung are doing, it's obvious that they are making their own OS of Android, and that is probably why they having some Tizen phones out, and experimenting with Tizen OS. They are mowing away from Google, and soon we will not see much left from the Android experience at all.
And seriously, how much do you use all their very strange feature they add to their phones? To be honest, the only good they are doing is their camera app, it's the best I've ever tried of all camera apps available.
The rest of the features I hardly used more than once.
And I am tired to have to use different launcher to hide all the Samsung bloatware and other junk.
So it will be a pleasure to switch to Sony, and their new way of thinking. They do very light changes to stock android, and will update all their devices very, very fast. In fact, fastest of all manufacturers.
And the changes they do are only good things, like adding a new music player, video player and so on. Nothing big. And Sony is very open now, and very optimistic to hacking and fan developing. So there is a lot of development going on for Sony devices in the "Android scene".
And the build quality on the latest Xperia devices is just awesome.
So I can not see any disadvantages switching to Sony from Samsung at all, only advantages.