I won't say very safe, but i would state that the advantages of usdt is top notch, and is more than its disadvantages.

On a scenario, with USDT, you have an opportunity to avoid a dump, by selling your btc, or etherum to usdt pairs.
But on another scenario, staying and too comfortable in usdt could lead you to miss out on a potential pump.

You ability and speed to move in and out of usdt will prove pivotal in defining how safe tether or usdt for each individual.