...and they lose online multiplayer.
Seriously tho, if I had either machine, I an not sure if I'd pay for Live/PS+. Most of the games I bought on PS3 and play on nonNintendo systems are single player experiences. Sure some have a multiplayer component, but they are designed and primarily played as solo games.
However, its not that much as a yearly fee and it does offer free games each month. So I probably would just get it. But I wonder how many people own a X360/Xbone and only got Live for netflix usage.