BA used to use gate A3 at VIE. For those on an out-and-back to start an ex-VIE premium special, it was a no brainer. Out of the plane into the gate area, turn right for security, back into the gate area, get on plane, leave.
Now all BA flights have been enhanced to the area at VIE servicing flights to Warsaw, Budapest, Ljublana and Prague. 99% of the time, BA now use gate A49.
Inbound to VIE, the bus takes you to the terminal.
Implications for out-and-backers? Theoretically OK. According to my self-printed BP, the VIE gate closes 10 minutes before scheduled take off time.
However, I'm not sure what happens if the inbound plane is delayed - like yesterday when 10 minutes after the theoretical Gate Closed time at the dreaded T4, there was no sign of anybody in a BA uniform

- and the eventual explanation of 'shortage of ground staff' was unwelcome.
Could the VIE gate close before a delayed incoming passenger took the bus, sprinted through transit and on to A49?
Surely BA is not learning from O'Liary by not using the airbridge? BA at VIE says the change is because of Customs demands, a suggestion I find less than credible.