Yes, i am currently seeing that now.
It may not have the sharpness of my 50 on the closer end but the images it produce are exquisite, with a very delicate rendering. It is like eating a delicate slice of angus or kobe fatty beef compared to the more inexpensive but delicious australian variety. Bith are tasty, both are filling. But the gourmet beef will taste better in a very aubtle way when you serve it medium rare. Seared outside but juicy inside. Marinating it in wine will just ruin the delicate taste.
This is the subtlety of the noct! It is smooth but never vulgar. The ART 50 from sigma is just brutally sharp wide open. It is made with a different mindset in priority and is a workhorse of a lens when you just need a no bs lens to bring on an important shoot.
The kiddie photo is at f/2? This lens is already pretty good at f/1.4 and very good at f/2. The characteristics change a lot in between these apertures. At f/2.8 it is optically perfect in my opinion