they are strong but have a week point in the check plate i was unlucky enough
to get a sick under the front wheel and push it into the check plate bending it, but thats nothing a hammer and block of timber cant fix, but if it does that and misses the step it can hit the sill which happened to me also, thats going to need a panel beater to fix that , but that was rather unlucky.
in the end its worth it and if your handy with a welder you could probably add an extra rail directly under the sill, (still on my to do list)
hope this helps.
but the steps as is will protect the sill if you come down heavy on rocks or logs, i was unlucky to have them spear upwards