I thought Tarkin was a very nice surprise in Rogue One. I also think Guy Henry was the perfect choice for the role. I don't have any ethical issue with the CGI make up. Frankly, it felt more like a tribute to Cushing than anything else. Henry really does sound an awful lot like Cushing anyway. I even said as much to my wife, years back, the first time he spoke during the Harry Potter films.
I don't think practical makeup would have worked as well, but I always thought the actor they made up for the prequel cameo looked terrible.