A couple weeks ago I replaced the stock 500GB 7200rpm disk with a 750GB Seagate Momentus XT "hybrid" disk on my mid 2010 MBP 15". While not as fast as a pure SSD would have been, I do notice a speed up in boot times and program loading with the hybrid drive. The MBP is used mostly for work writing tests for custom programming tools in Windows (running in Parallels) and Linux (via remote shell and VNC).
I needed to upgrade the HD as all my virtual Windows machines were pushing the stock drive to near capacity. I'm happy with the capacity and performance boost with the hybrid drive.
Now I want a 16GB RAM 768GB MBP with Retina