Here's a screencast for another GH definition that doesn't use an offset curve. It may improve the accuracy of the cut. The file is attached below.
Here's one more go at the tab problem. Attached is a Rhinoscript that does the same thing as the previous GH definition. It uses the profile curve to generate the interrupted profile curve. There are three successive command line requests. The first is to select the profile curve, the second is to indicate the number of tabs to be placed and the third is to specify the tab length. The result is nearly instantaneous and may ultimately be easier to implement than the GH method. If you want the options to be 'sticky' and carry over from the previous use I can add that. The easiest way to test the file is to just drop it onto an open Rhino window. This will immediately put the script on the command line. If it proves useful you may want to embed it in a toolbar button. Look at the Rhino Help file for info on how to use Load Script and Run Script commands if you're not already familiar with them. Let me know if you need any further help with the script.