Having been camping with these for 3 years now I have just purchased some more due to recently acquiring an extension for our Outwell Oakland XL.
Initially they were used with an other brand of tent but during an Easter trip to Tenby we experienced some severe winds. When I say severe the tent poles were bent and the tent was rendered unusable BUT the pegs held firm despite being in some rather wet muddy ground. Upon our return the tent was deemed faulty by the manufacturer and I am thankful for the pegs as the tent could quite literally have blown down the field with us in it!
They are now used with our trusty Oakland and are often hammered into wet, muddy ground or rock hard sun dried ground dependent on the good old British 'Summer'. At no point have they ever failed us and we have to have them bend although I would imagine you would need some serious strength to bend these bad boys. You really need to ensure you have an extractor as come the day when the tent comes down the most difficult job is getting these out of the ground!!
Overall they are highly recommended and despite being a little more expensive than others they are worth the extra cash just for the piece of mind.