Hello :), imo its a good idea to add new gamemodes, because it will make the game more interessting and it will force players to play new gametypes :).
I think it might be a bit boring to play CTF, insta CTF and rocket CTF. What about adding at least one new gametype: TDM or CA.
This is a good idea, because clans have to learn new things, try something out. IMO its a good idea to force players to new things 
, because otherwise some of them will never try something else.
I think of deleting all rockets and add TDM, and if the sun is shining delete insta and add CA.
Maybe some players will play TDM if you add this, maybe you will help oa with this.
This is just a try 
all the best
a_clown :o)
)
