For the last 10 years ive had the bikes on the roof of the car, racks and thule 591’s never hit a barrier or lost a bike, what i did lose was about £1k in value off the car when i traded it in, some of it my fault. I left the bars on and somehow they slid a little taking the paintwork from where they gripped into the roof. Also there was the issue with the roof, mine was trashed, 2 dents only tiny dents where i had dropped the one bike in the rain and the chainring caught the roof edge. Paintwork as i had driven home on the motorway, bits of stone/mud from the bikes had scratched the paintwork and tbh it was fairly obivous.
When i got my new car tbh i was going to go back to the roof, but silly glass roof doesn’t allow roofbars unless they are manufacture supplied.
So i went towbar and thule euroway g2 i think it is, yes expensive but does the job and so much better than i thought. I ditched the car due to a motorcyclist coming at me a few weeks back, the bikes and rack fully intact and no damage. Plus everyone i talk to when i stopped at services where more interested in how the rack worked and how i could get stuff out the boot, clever little latching system on the towbar rack.
Bikes are solid and less cross wind issues. Im sold on towbar racks and will have my next car with a towbar.