Nice snag. I dig on the 51s, especially since they can be grabbed on the super cheap (sub-$100 for a vintage FP in worker order is generally a great deal).
What people have been saying about Noodlers is still true. However, a lot of the issues with Noodlers can be easily fixed and the extra effort is entirely worth it. It shades beautifully, comes in a ridiculous number of colors, and is incredibly cheap ($6 for 3.5oz, which is a ton of ink). I also like it because it flushes incredibly easily, so changing ink colors is a piece of cake, allowing changing from black or brown to lighter colors.
Waterman, Montblanc, and J. Herbin are also great inks. I use Waterman black for my daily use pen (singing things, writing on unknown paper, etc), since I have yet to have issues with it on any paper. Noodlers is my personal use/fun inks, since it requires known paper (with minimal feathering and bleeding) to work best.