Celestial Lions: New Fluff and the new C:SM book

So when I decided to play Space Marines I was looking for a cool themed chapter and one that would give me flexibility. After I saw some awesome 3rd party accessory items with a lion theme to them I had to look up Space Marine chapters that had to do with Lions. 

To many troops?

So is there a such thing as having to many troops in a game of 40k?