I have the Nikor 50mm 1.4 and the Sigma 30mm 1.4 on a D300S. I love both of them especially for low light indoor shooting. Both give beautiful creamy bokeh when used wide open although the Sigma has a slightly yellow/green tinge that I fix in post. I'm guessing the Nikor 35mm color fidelity is just as good as the 50mm 1.4. I love the wider angle for getting a bigger picture (like my 2 kids playing for instance) while still blurring out the background nicely (like all their messy toys and general household disarray). Close ups are a little distorted unless you like the big nose fishy look. That's where the 50mm 1.4 is amazing. Closeups, tightly framed candid indoor portraits are beautiful with this lens. I'd keep both if you can.