Vatican - audio guided tour or group tour?

Hello,

It seems that I am not able to join the earlier group tour at the Vatican mid October due to the train arriving just shortly before the tour starts.

I am reluctant to book the afternoon tour, because that cuts it "very" close to the ships all aboard time (or my comfort zone).

I was set on doing a "smaller" group tour, but now might have to opt for a self guided audio tour. Has anyone done that at the Vatican/Sistine Chapel? I know there is a great value for a tour guide, so I would be willing to pay for a guided group tour and just leave 15 mins earlier to make my way back. I like to leave an hour buffer in between all aboard and arriving at the "ship". But if you have had great experience with their audio guided tour, I would just book that and enjoy the afternoon strolling through parts of Rome.

Any feedback is much appreciated!