I will be keeping an eye on this post as I am sort of in the same position. I have been looking at Sundowner and never heard of the paint thing causing corrosion?!?!!
We had (recently got stolen) a 2h bp that we have had for 10 years. So now we are in the market for something bigger, as our family has grown. We are looking for a 3-4 horse with small living quarters or weekend package. Or a stock trailer, either one being gn though.
We have been looking at the Exiss line of trailers. We know a couple of people who have them and they have been very happy with them. As far as price they are very competative to other alum trailers with similar features.
Personally, I don't like the latches on Sooner trailers, they have drop pins. But that is because I just prefer to be able to push the divider shut. Apparently they call that a "slam" latch.
I also prefer an alum trailer if I am getting any type of living quarter or weekend package just for the weight factor.
Of course, if we chose to go with some form of stock trailer, I am perfectly happy with steel, although it will be more up keep.
Hope those opinions help, and I hope you find what you are looking for.