It's okay for P&S applications (the Canon RS was clearly a consumer camera) but not really suited for any critical work.
Oy...
http://www.mir.com.my/rb/photography/hardwares/classics/eos/EOS-1nRS/index.htm
Perhaps you meant the EOS RT. But that one, too, is overall no less suitable for "critical work" than the EOS 630 on which it's based. And for some specialized tasks, it's better suited. Yes, I own one. Used to have a 630, too.
The Sony SLT's aren't the same sort of beast as the RT and 1N RS at all. In the Sony cameras, the pellicle is essentially a kludge to permit a different arrangement of the AF system in a mirrorless camera. It doesn't benefit the viewing system at all; from the user's perspective, the cameras offer just another EVF, not the worst but not the best either, and with all the characteristic drawbacks of EVFs.
In the Canons, OTOH, the purpose of the pellicle mirror is to give you a clear, continuous optical view without any blackout at the moment of exposure. And, when you want/need it, a "real time" mode with a release lag that's about half that of a film M-Leica and a small fraction of that of a high-end DSLR.
EDIT: Just to be clear, I know Jan wasn't making any claim about the Sony cameras compared to the Canons. It's worth thinking about the differences, though. The SLTs are OK cameras, and decent value for money. But despite all the hype about pellicle mirrors, from a functional perspective the user doesn't gain that much, just a slightly different set of tradeoffs between low-end DSLRs and smaller mirrorless system cameras.