Just look at the recent top tournament lists there (www.discountgamesinc.com/tournaments) to get a glimpse of this. Makeda3 is almost always taken with at least one derp, and so are Xerxis2 and Rasheth among the most popular lists.
The difference nowadays is that you don't *need* double derp turtle in both lists to be competitive, but they’re still incredibly efficient models that take buffs super well. I don’t see derps losing any of their competitive edge anytime soon, but since the CID there’s many more competitive options so you have some compelling alternatives.
The problem is that most Derp lists don't bring some of the "niche" tech needed to win. They have no anti healing, no anti tough, no anti magic, nothing to stop soul collection... Also every few months shooting gets worse as they release YET ANOTHER ultra cheap shield guard unit, each one getting progressively better.
So is the turtle still great? Yes, but thanks to the meta state we don't care.