The ernst stuff is nice, if a bit pricey. I also don't like their longest rails (18"?). They aren't stiff enough to support a full load of sockets. I settled on the medium length (13"?), and even they struggle when fully loaded with 1/2" deep impact sockets. It's not that they'll break or the sockets will fall off, there is just more flex than I would like. I actually emailed them and suggested they mold the rails over a strip of steel to stiffen them up, but they haven't listened.
One of the advantages is that they have an out of the box solution to stand vertically - three narrow bases with grooves that the rails snap into. One at each end and one in the middle, perpendicular to the socket rails. Nothing that couldn't be relatively easily to functionally duplicate for other rail types, but it's convenient. I spent a bunch on them for most of my sockets and while I like them, I constantly wonder of there isn't a cheaper / better solution.
I want rails to take to the work - just how I roll. Some guys do the same or similar kinds of jobs enough that they know what they need for each job. My work is too varied for that, so I typically bring a couple rails to the project, and work from them until I run into something I didn't expect - ie I'll have my 3/8" semi deeps and 1/2" swivel rails..and then bump into an unexpected torx or Allen fastener.. cursing ensues, back to the box. Still seems like the fastest way for me.
ahm