So figured id just give my experience with synced notifications, more data the better. I only use it for a handful of apps. Most important being sms on desktop through the action center. They were hit or miss towards the end of rs1 development. I only have one computer i use, an asus zenbook, so I didnt install any rs1 builds until the very end of development when they were said to be stable. I need it to run flawlessly for work, and for peace of mind. I am very ocd about having a perfectly running machine. Everything was working great besides notifications. Sometimes they would come through delayed, sometimes not at all. Often not dismissing properly. I like to do clean installs once "RTM" is released, even if Its just a few insider builds that were installed consecutively. 90% of my installed programs are portable so its no big deal. I opted to use the refresh tool because I found it does a better job at wiping everything nice and clean, more so than a reset. Its seems to be the closest to a true clean install in my experience.
Anyway, after the refresh all notifications are working flawlessly. This is between a lumia 640 running 14393.82 and a zenbook running the same. They come in almost instantly and dismiss properly as well. Now, it obviously should not take a fresh install to work properly. The general populace cannot be expected to take such measures. With the new W.A.A.S model, everything is riding on consecutive updates not mucking anything up. Since windows (and any major OS) is now in what is arguably a perpetual state of beta (peeps are all feature junkies nowadays!) it will be interesting to see how it all plays out. I am of the more optimistic camp. Once a major update hits "rtm" , the cumulative updates will hopefully iron out any issues that remain. Rs1 does seem a lot more polished (under the hood and UI) than threshold. And now that OneCore is getting more mature, hopefully it is all up from here. Stability has to be number one!