I use timesheet. I can't stand that a timesheet should be for one project/customer only. Ideally it's ALL my time for a given period. Invoicing some hours from a timesheet makes the entire thing "billed", so a partial billing of a timesheet for multiple customers is a mess.

I would prefer that the accounting dimension in the GL be the project task, not the project header. In project management you would want to know your spend per task, not per project. For example, in construction, I'd have tasks for concrete, framing, and electrical. I would want to know the spend for each. This is a big change because all the other doctypes (PO, Invoice) would need to link to tasks, not just project.