Definitely durable. I grabbed the 07-08s RXs last Spring post-season for cheap and have put right around 50 days on them this season mostly doing park. They are super solid and everything but the backs and straps seem to be made out of metal, but they're not that heavy.
In fact I thought they were more of a mid-range binding instead of budget-level. I've stepped on the rachets a few times by accident but everything still works. Though one thing is I wish they were easier to push and keep out of the way when stepping in standing up.