For general street and travel photography, do you prefer a small or large setup?

Here I'm about to pull the trigger on a 40mm Sigma f1.4 (supposedly the sharpest lens ever made). But, it weighs in at 1.2kg and is over 150cm long.

For about the same price, I could get a tiny Ricoh GRIIIx (same 40mm equivalent focal length), which includes both the camera and the lens, and it fits in a pocket.

Obviously, the image quality from the big Sigma on a full frame camera is going to be better. But the question is, will it be enough better that it warrants the enormous size and weight difference?

Personally I can't decide, so I may just buy both.