Having used both I'd look into Moose rather than Spiffy, Moose being a lot more solid base.
The nicest thing about Spiffy is the way it handles $self for you. But that's done with a source filter, so... slightly fragile.
Starting a new project today, I'd go with Moose, and probably try out Method::Signatures. That pretty much brings Perl OO into the Century of the Fruitbat.