I've run into a lot of people who have tried it, and the results are mixed.  The ones who haven't had any problems say they don't notice much difference, and the rest have been cursing Microsoft ever since.  There really is no need for it, so why bother?
If you're having problems with 5.0, try downloading 5.01.  I haven't had IE crash on me in weeks (except for once, during my ill-advised AOHell experiment).