The size of the model has some bearing in whether or not the leading and trailing edge shapes matter. Also, there is a worthwhile reason to square off TEs.

First off, the size............ The smaller the model the lower it's Reynolds numbers. The smaller the Rn, the less impact (pun intended) the LE shape has. We all have seen the foamies cut out of sheets of foam. We all have seen how they fly. No real argument about LE shape for small models. Really.

Trailing edges are often left square for a reason. They're much easier to maintain when they aren't so thin they're weak and easy to damage. Their size also matters for much the same reasons the LE sizes matter. Good thing about TE's when they're squared off is they don't add enough drag that anyone notices.

So consider the size of your model when you make decisions about shapes. With smaller models, we really won't notice the differences in performance. In fact, if the models are small enough there aren't any.

What size do the models have to be for the shapes to matter? I think that's never been hypothesized or tested by modelers. Want to provide something useful to the discussion that's about to blow up? Offering observations of models you had would go a long way. Or if you've found something in a text that suggests where the thresholds are.................