Update to F11 or new install?

[Smith, Herb]

The upgrade guide says:

While upgrading from Fedora 10 is supported, you are more likely to have
a consistent experience by backing up your data and then installing this
release of Fedora 11 over your previous Fedora installation. 

Are there any expected downsides to doing an upgrade versus a complete
re-install?   What do they mean by "consistent experience" ?  I'd rather
do an upgrade, but if there will be some defecit in the final result,
then I'll consider the full install.  

What's the consensus from those who have upgraded versus doing an
re-install.  Is your experience "inconsistent" ?

Thanks,
Herb