Opinions ??? No shortage of those here ... Probably a good idea to ask Valiente about steel, he has a steel boat and seems to like it. I've never sailed a Bruce Roberts, so can't help you there. The company doesn't make the boats, they sell the plans and the boats are all home-built so quality varies wildly from boat to boat.
They are not great performers, but they're not designed to be. I think that the majority of owners are people who are a bit more individualistic than the average sailor.
There is a metal boat forum where you'll probably find some information on them... http://www.metalboatsociety.org/forum.htm