My family has an H&S aluminum stock trailer; we have cattle as well, and can't afford to have a dedicated horse trailer separate from a "cow hauler." Trailers
We've hauled everything from horses to cattle to new furniture in that trailer for years and never had a problem. Like all stock trailers, it'll probably rain in a bit, but if you're a little handy it isn't hard to put in some plexi "window panes."
We ended up making a few modifications to our trailer that I don't think would be necessary with what you're looking at, Puck. The ceiling is rather low for horses; although my little guys, both under 15 hands, both fit, they were less than comfortable with the lack of overhead space. That seems to be the main issue with true stock/cattle trailers, rather than stock-type trailers designed more with horses in mind (what you seem to be looking at). Dad and I ended up chopping the top and adding hollow square aluminum tubing to buy another few inches of clearance (fit the existing framing inside the new on top and bottom, bolted and welded in place), fit a strip of aluminum down the center of the now-wider gap at the sides to keep the horses from hanging their heads out, and added a panel of diamond plate to the front to take care of the new gap between the wall and the ceiling.
We also made a removable divider for the inside so that we can load two horses slant-load style if necessary, or separate cattle for a trip to the auction. We used a gate from TSC as a divider, and for extra padding we "upholstered" all the scary edges with foam pipe insulation tubing, held in place and covered with a layer of electrical tape. All probably tougher and sturdier than what would have come in a purpose-built horse trailer. Another addition is a layer of paint-on truck bed liner on the floor -- it pressure washes clean and gives the boys a little extra grip going down the road. The whole overhaul worked out really well -- I'll have to get some before and after pics. Most every show, a herd of dads ends up staring at it and asking Dad what his process was, lol.
Probably not the route for everyone, but it worked out really well for us and our situation.
Anyway, most folks in my area, unless they are real campaigners come show season, use stock trailers of one type or another. I find most horses load more readily into them because they seem more open and bright. Honestly, every road-trip horror story I've ever heard has involved horses in horse trailers, usually straight loads, not stock trailers. A tack room/dressing room would be nice, but we do just fine putting the trunk up in the truck bed and doing quick changes in the back of the trailer.
No, hauling in a stock trailer wouldn't scare or worry me in the least; no more than a road trip in any other style of trailer. We all know that, with horses, anything and everything can happen.