I'm thinking og buying a low-power-consumption...

I'm tempted to go with BigBlueButton - it seems to have everything and
promises to be easy to install.

Do anyone have experience running these things for practical use?

I don't have experience in *running* BBB, but in using and I'm very happy with this tool! I know  lot of video-conferencing systems and have special requirements, because I'm deaf and for every communication I need to see my sign language interpreters. BBB is the only systems/software I found (and I know a lot with more than five years of experience), with runs very stable, have low power consumption on user side, runs in Browser (without app), fulfill security and privacy requirements (including being open source) and is easy to use.

best regards

    Irmhild