Open source != patent free.
I'm not saying that it is patent encumbered, but just pointing out the flaw in your assumption. So long as there is a guarantee that it will be free to use forever, I see no reason why modern browsers shouldn't implement it. What's the downside?
A new Tektronix oscilloscope will work as well. When I was an undergrad my colleagues were convinced that you need analog ones to make proper measurements, but I've had great success using digital ones. I actually prefer them.
Without a definition of what "good" means or what your needs are, I don't think that anyone can give you any sort of advice. I personally would never use one that had to be controlled through a PC. Having to drag a laptop or something all around the electronics of an experiment would be a major pain. (I've only used them in the context of the detector and apparatus signals in physics experiments.)
If the general public sees no difference and doesn't care, why is one superior to the other?
"Who alone has reason to *lie himself out* of actuality? He who *suffers* from it." -- Friedrich Nietzsche