What is the RPM equivalent for a SSD drive performance?

I've been reading about hard disk drives performance and I've noticed that a lot of users agree that from the day-to-day point of view there isn't a huge difference in using SATA 3G or Sata 6G as long as you're using a regular spiing-mechanism HDD (link to forum). Yet most of them agreed that a mayor performance difference was noticed between 5400 and 7200 rpm HDDs (asume same cache size and SATA interface). I know that SSD drives don't have a spiing mechanism so there's no such thing as an rpm value for them, but if I wanted to compare a regular HDD to an SSD without having to know all the tecnichal random/sequential data access read/write values:

1. Is there a way to match all this technichal parameters to a rpm equivalent value for the SSD?
2. Is ther a way to match rpm and cache with the tecnichal random/sequential data access read/write values?
3. Would it be a bad idea trying to compare performance by just thinking about rpm values?
4. Why wasn't there a performance boost on regular HDDs after switching form SATA 3G to SATA 6G? What kept this change from being noticed? Why is it noticed on SSDs?