Death Trooper & Krennic

Does anyone is running DT + Krennic duo with empire team in arena. My question is, are they reliable with 4-5 *. It takes ages to stack shards to them. I was thinking about team: (L) Krennic, Death Trooper, Sh Trooper, Thrawn, TFP. First I need to invest in gear, but question is, is it worth to investing if they are 4*. I'm trying to buy shards from shop, but still long way to 7*. Thanks for suggestions