I've never seen tasskr before. It looks simple and I like that and I particularly like the progress bars--this seems to be begging for a phone client. However, I didn't sign up even for a free account because I don't see how to use this with my smartphone. You may or may not support phone, but it was pretty easy for me to conclude that you don't and also don't plan to, either.
I've been slowly moving through the various online task managers looking for one that "fits" and most don't work out, but some sort of phone support effort has become requisite before I will even bother because that's what I'm looking for. Frankly, I'm also sort of burned out looking for task managers and hunting for something that works well in the desktop and on the phone--there are so many half-there implementations that I just don't chase them all anymore.