Pricing philosophy
At $5 to $12.50 per user per month, Trello's per-seat cost looks low, and for a single board with a single client, it often is. The cracks show once you're running multiple client projects. Single-board guests are free, but the moment a guest needs visibility across boards, which happens fast in a real agency, they become a billed seat.
Where it breaks for agencies
Trello has no native approval concept. Agencies bolt this on with Power-Ups, third-party add-ons with their own setup, learning curve, and sometimes their own cost. The result is a patchwork, the board looks simple, but the actual delivery workflow lives partly in Trello and partly in whatever Power-Up you've wired up.
There's nothing in Trello that connects a finished, approved card to a billing event. For agencies running more than a board or two, that disconnect becomes the same end-of-month scramble Scopeyard was built to remove.
What we otherwise really like about Trello
Trello's simplicity is a feature, not a bug. For a small team running one or two client boards, nothing is faster to set up or easier for a client to understand at a glance. The Power-Up ecosystem is also genuinely useful once you know what you need, calendar views, time tracking, custom fields, it's all there if you go looking. Plenty of agencies start here for good reason, they just tend to outgrow the approval and billing side first.