That is the issue here.
We have the previous previous version of Numbers and Pages. Neither one of the new versions can open "2 versions ago" documents or spreadsheets.
But, they do have the previous version available to "open with" so you can cut and paste.
No other problems. Except, to get Mavericks, you have to have an AppleID. I reactivated my 2007 ID and it downloaded and updated the OS, without any problem.
I have Mavericks on all my Macs (iMac 'late 2007', Mac Mini 'Mid 2012', Macbook 'Early 2008', MacBook Pro 'late 2012', MacBookPro 'Late 2013'), except the hackintosh... which isn't 64bit and can't run it.
It actually is very nice and walls in the garden a bit more... but the workarounds that existed before that were kind of enabled by default, are now not enabled by default. This is good for the general health of machines and protection from idiot users from themselves. Still not a problem for those that wish to take thing into their own hands.
Forgot, on older machines... (like the 2008 and 2007) you will need to max out the memory. I had to put 4GB in my iMac and 4GB in the Macbook. Otherwise, they sometimes seemed a bit sluggish.