I have used to use drop-down terminals. Nowadays I work almost solely on terminal and I do not have any reason to ever hide it. But I really understand what you are asking.

One more you didn't mention: Yeahconsole [https://github.com/rduplain/yeahconsole]. It is simpler than these others (no tabs, no configs).

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Yeahconsole is using system's xterm (osso-xterm is not working)
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Guake is missing: python-vte
Maemo's vte (version 0.16.14) doesn't have python bindings. Newer vte needs new glib (not issue) and new gtk (serial issue).
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yakuake needs kdelibs. Seems a big deal (I don't even tried)
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tilda needs libconfuse-dev (trivial, not yet in extras)
tilda-1.1.8 needs libvte-2.90-dev

tilda-0.09.2 I got this running

It is using old libvte.
Issues
*It will not write configuration file if not used configuration wizard and 'OK'-button, but this button is out of the screen. (workaround copy config from another computer)
*pressing letters gives UPPERCASE and with shift lowercase (this is known issue of that libvte)
*transparency is not working
*it is fullscreen (no matter of height,width)
*pos_x, pos_y is not working (as it is fullscreen)
*it is not totally fullscreen: system's bar is covering it
*changing background color is not working
*animation is not working
*If there are too many tabs, most left one can't be accessed (because of the system's menu, clock, battery etc)

These (and variants) can be used as a key:
key = "Control+p"
key = "None+p"

These (and variants) can NOT be used as a key:
key = "None+å"
key = "Control+Shift+p"
key = "Shift+p"

Additionally there are these:
Ctrl-Shift-T (New Tab),
Ctrl-Shift-PageUp (Next Tab), (can't be pressed with default layout)
Ctrl-Shift-PageDown (Prev Tab) (can't be pressed with default layout)

Do you think you are still interested in about it?