Depends what you listen to,
extremely heavy and extremely soft sounds, for me, have definite unintended distortion at peaks and busy moments...
Depends on your setup if you can hear that though.
If space is relatively unlimited or you want to archive off your CD's lossless is the way to go. but if you're just listening to stuff on the go, it's not worth the space hit you get.
You can always convert the files down*, change your iTunes cd ripping type, highlight the tracks you have in ALAC and you should be able to select "Make MP3 Version" (or similar)
There is plenty of software out there to do this for you too on all major OS's...
*you can't add what isn't there.