I bought a single 40 (w/side panels and glass door) around 1999 - then in 2005 I bought a single 30 in the same configuration. Both are on casters ( a *big* plus). They are built pretty well. I think their main strength is good looks - - they are a bit on the pricey side, and if you're mostly concerned about great sonics from a rack, look elsewhere. As for me, looks are important, I'm happy with mine and would buy them again.
Salamander Quality
I'm looking at the Salamander Synergy twin 40, but can't find much as far as reviews on it. I'm mainly looking toward the twin 40 for the design. Mobility is important & the twin 40 can be had with the saturn casters. Quality...as far as fit & finish are my concerns with the salamander. Before a plop down $1500, I want to be making the right choice