In case you want to share the source code for free I think you should use GitHub, maybe some people would contribute to it and develop it further.
But in case you mean you want to sell the software or even share it for free, there is already an official level editor that is interface with AppGameKit and I can run my level from the editor in AppGameKit with a click of a button and use simple commands to address any sprite in the level. I'm happy with that one.
https://www.appgamekit.com/visual-editor
I don't think we should kill an officially supported editor with a free option that may even going to lack development after. Of course everyone is free to try and experiment I'm only sharing my opinion on "do we need an other map editor". At least for Tier 1, but it would be interesting to see a map editor to be used with AGKSharp:
http://madbit.bplaced.com/?page_id=136
I don't personally expect the Visual Editor going to get AGKSharp support in the near future but in my opinion AGKSharp must become an official flavour of AppGameKit and it would be interesting to see a map editor right from the bath to use.