I have noticed that in the last releases the background-mode has disappeared from konsole. It's a pity, because it was very useful.

You may say that I can have the same with yakuake. It's true, but at the price of loosing some advantages of konsole over yakuake.
For instance: in konsole I can start a new profile using a shortcut: it opens a new tab with the new profile. In yakuake if I right-click and choose switch profile only the looks changes.

I have different profiles to work locally or remotely (through telnet). When I need to work with the remote computer in konsole, I just press the shortcut and immediately I have a new tab with a different look and a different connection. I can't do that with yakuake. Or, at least, I don't know how.