In reply to marky:
Cars hired from the Swiss side are all now registered in Germany (at least the last half a dozen times friends have come to us via Geneva airport they have been) specifically not to fall foul of the customs issue about non-Swiss nationals taking Swiss cars out of the country.
I think it's always better hiring Swiss side as its easier getting around the airport, and having a Vignette makes everything much less stressful - especially helpful if you're dropping it off against the clock. Plus in winter you get chains and winter tyres as standard. I think it might even be less eye-wateringly expensive now with the CHF exchange rate.
Although that said I was in the airport killing time after a cancelled flight on Monday and bought a trail magazine - tagged as 7eur in France - it was only when I checked my receipt, and the microscopic foreign pricing on the spine of the magazine that I realised it cost 15.5CHFs. Almost double!
Post edited at 10:00