CAUTION: the extent of my testing (not much) shows that SmartSleep doesn't properly support encrypted disk swap. the pmset command that supports the hardware for this needs an extra bit to properly support hibernation with encrypted swap. My test: default, my 'hibernate mode' is 7. This is the combination of hibernate (1) + sleep (2) + encrypted (4). SmartSleep set it to 3 when told to sleep+hibernate, which would certainly fail to come out of hibernation properly if you have encryption enabled.
That said, Smart Sleep is a great idea.
Saving the memory to disk (hibernate) every time is a waste if you're just going to wake it up soon anyway, which doesn't use the disk. But, be forewarned that the intel-based machines don't have a small internal battery for swapping batteries so they lose power when you remove the battery. Not usually a problem, but if you don't have hibernation enabled, it will effectively reboot, having died in sleep.
If it included this warning, and fixed the issue with encryption, I'd use it.