I think a second cat will be a wonderful idea, it will provide companionship for Gizmo when you aren't home and a playmate for when you are just too tired or sleeping, not to mention they get great exersise chasing each other around! There will be an adjustment period for the 2 to get used to each other and Gizmo may act strange, but once the adjustment is made, Gizmo will most likely be the same old cat except with a new friend who I'm sure he'll cuddle with a lot. As long as his cuddling with a new cat wouldn't make you jealous, I say go for it, there is enough love to go around!