Yes, the current C70 is noticeably more supple & less crashy on the 17"s than on 18"s, over the typical lousy surfaces on local or country roads. I continued to run the recommended 38PSI pressures when I swapped the wheels over. That said, even when I ran the old C70 on its 17"s at more like 34/31 so it was a bit softer, I still knew about it when on a lousy road - just not as much.
This is what comes up on a quick search on the 'Bay:
https://www.ebay.co.uk/itm/202217537896
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Current: 2012 C70 D3 SE Lux Solstice Geartronic, Caspian Blue.
Also: 2002 Audi A2 TDI SE, Crystal Blue
Previous: 2008 C70 D5 SE manual, Flint Grey.