I have been using this for almost two years now. I am not sure if there are any other users but I find it very convenient. (Disclaimer: I wrote the extension).
Yes, `hledger' is based on double entry bookkeeping. But we do not use the Credit and Debit conventions. Instead we use negative numbers to imply deduction in the balance of an account. Each journal entry must be balanced.
Always be invested in the market but make sure that when you need the money that you have invested, it is there for you to spend. It doesn't make sense to keep in the money in the market when you know that you will be in loss when you will have to take it out.