Merhow has been around a loonnng time, so they must be doing something right.  A friend of mine had a 2H BP steel one that was a 1970's model and it had held up rather well considering it was kept in Fla (under cover).

I believe they mostly make Alum skin trailers now and I'm not a fan of any brand of those due to electrolysis that starts when you put 2 unlike metals together.  However, to each their own.....  A good friend of mine that builds trailers (worked for Sundowner for years) told me he felt a well made steel trailer was a much better buy than the alum skin ones.

 But I also think the industry has made great strides in reducing the issue with electrolosis. Each trailer has its pros cons and you need to decide what works best for your situation.