But credit generosity may be partly a function of the economy, and it's hard to say what would happen if times get hard.
Things like 0% BT offers and high CLs may not always be there.
As long as your other cards are kept in check with low balances as well, very doubtful. There is little risk in a charge of 18 each month opposed to the overall CL. CLD is an action related to adverse risk factors.