Yes Gerald, I agree with you about the internal battery.
Especially when travelling by plane, one can avoid trouble when the batteries are hidden in a case.
This recent post shows a prototype of the proposed battery pack (warning: link goes to Facebook!).
Until now, I never used an ATU when portable and I never missed one, since I only use resonant antennas, like the portable 7-band EFHW antenna.
Apart of the lower weight, one thing less that may break.
73 Stephan