Why would anyone purchase an upper control arm that has to be removed to make adjustments? The eccentrics don't offer a lot of adjustment in the grand scheme of things. There are many better choices on the market.
Totally agree. Although most people really don't need an adjustable UCA at all, just one that has more caster built in. If you need an adjustable UCA then getting a "double adjustable" UCA that can be adjusted on the car makes more sense. And if you don't need an adjustable UCA using one with the additional built in caster and that uses a bushing instead of a heim makes more sense. The alignments will be easier because you just use the stock eccentric bolts and the bushings are pretty much hassle free and will outlast the heims many times over.
But live and learn right? I only know figured that out after being hassled by setting the alignment on a set of UCA's I had to adjust off the car. And after wiping out a set of heims after 7k miles of street driving and having to do it again.