OK, then, let's ship with several predefined task-oriented toolbars and allow the user to modify any of them by adding or removing tools. I guess at this level it's basically the same as Jon Cruz and you propose, except that I don't want to add as many new tools as you do :)

It doesn't hurt to be prepared. :)

Yes. For example, a drop-down with a list of LPEs with some preset parameters and a "last used LPE" entry, and separately from that a drop-down with profiles as in your mockup, implemented as pattern-on-path LPE (and therefore disabling the LPE chooser, until we can support more than one LPE per path).

Actually, the issue I'm pondering is "mode": these tools would basically be used for at least 3 types of functions: - normal lines, with nothing fancy save eventual dots and such - LPE, which is what you're proposing - And let's not forget drawing non-stroke shapes

Each of the 3 modes may have its own settings. To tell you the truth, I've always wanted dashes and markers accessible from the top-level interface. In the meantime, LPEs have the issue that although my proposal simply involves saving a bunch of shapes and shipping them with Inkscape, some people may come up with shape generators, such as waves etc., with different sets of parameters.

So what I'm pondering: do I make separate modes, like with Tweak tool, with different options appearing for each (is that a problem?), or do I keep it simple (but limited)? I'll probably try to come up with an interface for each option.

This is a relatively minor point - but Calligraphic pen works fine using the current fill color for its "strokes" and nobody complained so far :)

The difference is that calligraphic pens aren't used for different modes. :P Most people only do one thing with them: creating complex lines.