Geez! Attack of the Super Taks

Actually, when you run the calculator and do some divisions, like:

50mm/1.8 = 27.8mm --- IMO NWW calculating
50mm/1.7 = 29.4mm --- your present, standard glass
50mm/1.4 = 35.7mm --- about 40% more glass than your psg

So the Q is, what do you want it for?

A couple of answers came to mind, viz:
Let in more light. (Sub-Qs: is this an aim? How good is the IQ wide open?)
Better bokeh. (Sub-Q: will it be?)

Apart from this, my answer is, I dunno.

A?m.