You likely will not see signification difference between them. The large router manufactures have figured out the details of optimizing these devices over the years so the difference between devices is small.
The key reason you find positive and negative reviews on all products is wireless is greatly affected by someone house and their neighbors. Why certain routers work better in certain houses is a mystery. What you want to watch for in reviews are a large number of people complaining about total failures. All companies have bad products now and then.
On top of this you can not always be sure what is really being reviewed. The rt-1200 has 4 or 5 models just in 2 years. There are multiple that even have "G" letters on the...