I had this debate for like 6 months before. theres a few things to think about though. But the main reason I decide to get another chin was that I did want Tum Tum to have another friend, which somehow turned out to be his half brother since I got him from the same breeder. lol
It is true that in some cases that chins may never bond. So if your thinking about a new chin, you need to consider many things such has the time, the cost to tend for another chin, and the possibility of additional costs if the chins do not bond as you hope them too. After reviewing and researching, I decided to take a chance knowing what the worst case scenario was. The bonding itself takes time and patience. But luckily it worked out so well. Now my 2 boys always sleep together. Its just too cute!
if you spend time to at least interact daily with your chin, im sure it won't get bored. Tum Tum was just fine since he had alot of toys and I always interacted with him daily. But since i began working full time, I wanted him to at least have someone around. He seems very happy. They both do! =D good luck on deciding. It takes some thought. Best case is that your new chin will love the existing chin. Worst case is that they will need to be in 2 separate cages. =)
good luck!