Hi Maximilian
Ordinarily the Board doesn't permit users who have no posting history to post links in their first threads (we get a lot of spammers doing this) but I have checked out your link and I am happy for this post to remain. Other moderators may have a different attitude, however.
Having reviewed the available information on your add-in (which is freely available as a download and indeed is free to use currently - please note for anyone reading this I have not downloaded this product as it requires installation) I am a little confused about your target market: you say it is for advanced users but it is advanced users who by definition do not require such an add-in.
I can create my own formulas without VBA currently too and without a Cobble add-in - judicious use of workbook names, cell comments, helper cells explaining purpose and in formula comments using the N() function serve me extremely well when it comes to explaining function. I also wouldn't have a distribution headache then if I wanted to share my formulas with a colleague as they just need a copy of Excel on their computer and nothing else.
I also rather like VBA when it comes to defining my own functions: I can write ample and descriptive comments to accompany the code and once again I know that distribution will be completely painless.
Perhaps I missed something on your site and there are more complex cases than the highlighted Interpolation function where the Cobble add-in can be used?
