Is RAM upgrade worth it if I have an SSD already? I recently purchased a Macbook Pro.  I had an SSD from my last computer which I formatted, installed into my Mac, and used as my one and only HD (I don't need that much space so I didn't opt to do the upgrade where people pull out their optical drive).

I'm not much of a hardware guy - my knowledge is limited to basic understanding of where my data is hiding and how to swap parts.  I do work in Eclipse though, and I'm noticing that my RAM usage is near 100% (I still have the default 4gb installed).

I'm considering going for the 8gb install, but I'm wondering, Is upgrading the RAM worth it if I have an SSD already?  I know that when RAM is full it will use swap space on the hard drive so I don't know if it would benefit me to get an SSD or not...

I know there are some similar questions out there, but they all seem to focus on "Should I get RAM or SSD."  I've got the SSD, I just want to know if the RAM would provide any increase in performance.
RAM still is a lot faster than any SSD which you use in your Mac. RAM has a shorter access times and much higher transfer rates:



[table]

The SATA interface by which the hard disk is connected limits the throughput to a theoretical maximum of 6Gbit/s (600MB/s) for SATA3.

You can determine how much the page outs are written to the disk by taking a look at the Activity Monitor. I try to keep the ratio at a maximum of 10/1 (page in/page out). The more page outs you have, the more like a RAM upgrade will benefit you.