As I already mentioned on the Simplenote thread, I use CN for task lists, too.  Let me throw in my vote for this collection of features.

Yes!  I keep one instance open for planning and projects in general (daily task lists),  one for strictly legal, and one for personal notes and writing (as a hobby and eventually to monetize that).  This is on my Windows laptop, and each ties to Simplenote accounts I can, and do, use on multiple other devices, most frequently iPad and I Phone.  Each has its own Independent Cintanotes file.  With the tags it can work very well.

My only gripe is that, when I need to reboot the Windows machine (after installs / updates), opening the multiple CN files is problematic.  I use the new virtual desktops feature under Win10 (similar to the Mac desktops and KDE's desktops), and the window to open the file gets "lost." I would like to click on a recent file and be able to have it easily open in a new window instead of having it always replace the existing open file, which I want to keep open!

(But, once they are open, it works great!  This is more of a UI problem than anything else.  No major architecture changes are needed to fix this, but the fix would definitely add value!)