i think if we only have small until middle balance of xrp, then its no problem to use a exchange wallet but if we have xrp worth with 1 btc then i think its not safe as exchange could have any problem in any time. so its still good if we can found one xrp offline wallet to save our xrp balance. unfortunately, until now, i am not found xrp wallet and i am not yet trying to safe my xrp balance into github like above me said because my xrp balance is not much.