I've been using beancount for my personal finances for about 6 months, and will probably start to use it for business finances in the future.
But I wanted a budgeting tool that fit in with the plain-text paradigm, and beancount has no native budgeting feature. I used a spreadsheet for a while but quickly wanted something more custom than wrangling formulas and sheet layouts.
So I wrote one. It has a beancount converter using bean-query to allow comparing real spending (from beancount) against planned spending (which the tool is more built for).
Hope this is useful to someone else! Feel free to post in the github issues or reply here if you have suggestions, bugs, etc.
Best,
Frank