Something that I believe I have genuinely noticed is that some/many[1] Rationalists have a tendency to apply some sort of "rational" processing to any given idea and then reach their conclusion, but whether the processing that is actually applied (as opposed to what the person perceives themselves to have applied) is substantially different than standard human heuristic processing with post-hoc rationalization[2] (as opposed to rationalism) applied on top of it seems quite questionable to me.
[1] Any hypothesis is true to the degree that it is actually true - everyone is free to have their opinion, but the actual objective state of reality "is what it is".
[2] To what degree is the difference between Rationalist (as opposed to rational) and "normal" thinking & belief formation a function of differences before or after the post-hoc divide?
I suspect their are elements of both: I believe some members of the rationality community do routinely think in a different way to many other people, but I also believe that there is some post hoc rationalisation (as you put it) in the community as well.