I love PopClip, and have done quite a bit of hacking around with it. Once you get used to it and come to expect it popping up, the only annoyance is that all your handy tools aren’t there when you make a keyboard selection, or when you accidentally dismiss the popup before you choose the extension to run. Easily fixed, fortunately.
This is a companion discussion topic for the original entry at https://brettterpstra.com/2014/11/17/invoking-popclip-on-an-existing-selection