I had all sorts of problems with email after moving to Yosemite but (a) they seem to have gone away after a recent update, (b) they could well have been related to my company's IT incompetence rather than the OS or (c) I had probably done something stupid
My macbook pro is working fine with mavericks so I don't see the point of changing
especially as I use the canon software as well as lightroom and I assume that I would have to reinstall the software
if it's not broke leave it well alone![]()
A really irritating little feature is in Mac mail, they have changed the style of all the icons and the archive and trash icon, next to each other, are also similar and I keep hitting archive instead of trash :banghead: I KNOW, its a silly thing but its almost become a nervous twitch now.
If you upgrade, you don't need to reinstall anything.
Edit - I wouldn't install Yosemite on anything older than a Late 2008 MBP with 8GB, the first of the unibody's.
That's what mine is. AFAIK you cannot install it on anything older than 2008 due to graphics issues.

No problems here. I have a Mid 2009 2.8GHz 15" 8GB ram MacBook Pro, and swapped out it's hard drive for a Crucial M500 SSD. Did a clean install, then reinstalled everything and copied back all data after deactivating software on the original HD. Just incase I cloned the old HD first as insurance. My email accounts are IMAP, so easy to setup again. I don't mind doing this once a year. For an old Mac it's fast and snappy. No problems with the Epson R2400 drivers. Even on the initial Yosemite release I didn't have any wi-fi issues.
Edit - I wouldn't install Yosemite on anything older than a Late 2008 MBP with 8GB, the first of the unibody's.