We've had a
Pendle hang-on rack for years. It's been fine, even with four bikes, but it does take a while to put them all on, especially because I'm a bit neurotic about strapping them well, and padding them to prevent scratches.
Last year, a friend was selling off a
Pendle standard wheel-support rack. I bought it because I thought the wheel support design was better, although I've had annoying problems with the bolts that secure the arms dropping out. It's not that important because the bike itself secures the arms in place, but I keep having to buy more bolts. Once the rack is set up, it's quicker to load, but I have to disassemble it for storage because we don't have the space.
No worries on strength though, even with four bikes, on either rack. The hang-on one does bounce, but I think it's meant to. Rigidity is not the same thing as strength.