The following study, using a simplified expression, may give you an idea of how muPad ticks. On contrary to Maple it defaults to domain complex and like the symbolics in older versions of Mathcad the assume modifier is not always achieving the desired effect.
Mupad seems to consider much more special cases in its calculations, it "knows" that powers are not defined in real domain for every combination of base and exponent, etc. and while this may be correct from a mathematical point of view it can be annoying in everyday use.
Maybe the problem is, that MuPad first was developed by university mathematicians. maybe the problem is, that Mathcad and Prime are using a very old and limited version of muPad. As muPad now is owned by Mathworks, owners of MatLab and a competitor of PTC (really? can we still say that Mathcad Prime is a competitor of MatLab?) chances are low that symbolics in Prime will be enhanced in the near future.
