Real World Performance of Yosemite on Early 09 iMac

[pilotkid]

Hello all. I wanting to know the real world performance of having Yosemite on an Early 2009 iMac with the following specs. Ram: 6GB. Processor: Core 2 Duo @ 2.93GHz. Graphics: GeForce GT 120, 256MB. Its currently running OS X 10.7.5
Any information would be helpful, I'm asking this question for me neighbor who asked my opinion and I told him I knew exactly where to get my answer, you guys. haha.
Thanks in advance!

EDIT: The reason I said "real world performance" is because I know that Apple says it can but I just want to make sure it can smoothly.

 

[definitive]

Should work just fine, though I'd recommend doing a clean install (back up current work, create a USB installer, format, install, restore backups).

 

[pilotkid]

Should work just fine, though I'd recommend doing a clean install (back up current work, create a USB installer, format, install, restore backups).

I planned on telling him exactly what you said. I personally always do fresh installs on big OS X updates. Glad to know that it should work out for my neighbor.