At home, I run NCrunch pretty much vanilla and runnin tests per keystroke works beautifully.
At work, we have a solution with 127 projects, each with around 20 - 30 classes (on average). Running the tests on keystroke GENERALLY works, but I also often run into issues where the IDE slows down significantly.
I haven't noticed a whole bunch of issues with 1.38, but I would still like to request an execution mode that will use the files as they are on-disk.
Specifically, this allows Visual Studio all of the power it needs for syntax highlighting normally, while also keeping the test results "contiuously" updated.