if you have no issues running mavericks, then you most likely won't have any issues running yosemite. probably gonna want to do a clean install though.
I run Yosemite on a 2008 2.8 iMac with an ssd and 6gb of ram. I can't express how much better it runs than Mavericks. Smoother, quicker, both were fresh installs.
I'd go with an ssd any day versus a hybrid or Fusion. 500 gb Crucials are around $200 these days.
Agreed... have two mid 2009 MBP's one with 8G / 1TB SSD and the other with 8G / 750 HD and the speed is quite noticeable... It still runs OK on the HD MBP... But as per previous posts, the graphics are stuttery and laggy on both. But I believe thats a software issue and not hardware.