Not sure where your located but if your not in a anti gun state like CA , NY , CT etc I would wait a bit . I'm guessing there is going to be some good prices coming soon .
To your OQ I have heard nothing but good things about the M&P sport . Not sure it's a 1k rifle but when they were selling for $600 that was a good price for that AR . I'm a big fan of the foreword assist and dust cover . That being said I've never had to use the assist and the dust cover has only came in handy a couple a times . I'm of the thought , why not have them ? They do nothing to hinder you or the ability of the rifle and can only benefit you so why not have them for that off chance you need them . We all have those thing we keep in the car or in our house that we almost never need but keep them around just in case . I look at the foreword assist and dust cover the same way .
Why do I carry a 45 ? because they don't make a 46