Same experience here, I've had both the 12 and the 18 and frankly thought them to be poor at best. While a Silkie remains on my wish-list, I've had my fair share of DIY store and gardening type folding saws - and now a few Laplander's - all of which outshone the Opinel's. The blade on the Opi's seems to be soft as they bend very easily and thereafter don't fold too well, I also didn't like the locking mechanism on the 18.
Save your money
ATB
Ogri the trog