The only concern with updating is that with every OSX update, my macs run even slower, markedly with every update between Snow Leopard and Mavericks.

Definitely do the solid state upgrade. I did it on my mid-2010 MBP and turned a machine that was frustratingly close to unusable to quite adequate again. Just remember that not all solid state drives are created equal. I've had great success with Samsung drives in Macs, but one time tried an OCZ Vertex drive because I got a screaming deal on it and it turned out to be hardly faster than the old Winchester drive.