The "convert line to comment" feature is brilliant and it's used daily by us. But I think that a good compliment to this could be "section sub total", so from the last comment line down. It would be very useful for when you're quoting for many parts of a job.
So like this:
Bricks <- This exists as a comment line
Red Bricks £200 <- regular invoice line
Green Bricks £200 <- regular invoice line
Sub total £400 <- auto calculating subtotal line
Roofing <- This exists as a comment line
Truss £2000 <- regular invoice line
Tiles £5000 <- regular invoice line
Sub Total £7000 <- auto calculating subtotal line
Then totals in the footer as they are now.
Anyone +1 this?