OK here is my feedback. First some superficial stuff: Installshield is not going to fly with the market you want to make real money off, i.e. big organisations who want to deploy through Active Directory. The Office addin installer can be put as a merge module into an MSI, that will make the overall install experience much slicker. The instructions on the web page that opens after installation say to look in tab 'Add…
Sorry you did not find it helpful for the sheet you tried it on. We have not yet implemented a way of showing 2D nodes in an intuitive manner and this is one of our focuses for the next release.
You mention context - I think this presents possibly one of the biggest barriers to adoption. We included the ability to jump back to the cell in Excel as a result of similar feedback. There is definitely a lot more that can be done though.
You also allude to where we think Slate can be really powerful - documentation. If we were to implement the ability to annotate and group together nodes in Slate, you can give a general overview of how the spreadsheet is working, with the option to dive deeper and investigate the nitty gritty, if needs be. All too often you are given someone else's spreadsheet with no context, and this is where we think further value lies.
Would love to take this conversation to email to discuss further. I'm fraser@useslate.com