As far as seed germination, as @JohnnyPotseed said this is probably the wrong thread… and even better, there’s already a thread dedicated to precisely this topic. 
Germinating old Seeds has lots of good suggestions. DMSO sounds interesting, could quite possibly be the most effective of any method I’ve seen described. I’ll have to try that some time.
As far as I can tell, RO water is basically for suburban/urban growers who can’t trust their water supply, or for high-end hydroponic systems where you need to have 100% precision on everything about the water your plants are getting. Like you said, not sure it’s going to be all that useful if your water’s already pretty clean. It gives you full control over the precise makeup of the TDS, is all, which is helpful but not entirely necessary in soil.