I think the destroyer questions are definitely good practice and prepare you for common questions that could be tricky. I think your test is luck of the draw and I found that all the practice in QR I did (TopScore, Kaplan, and Destroyer) were very helpful. Most importantly, be sure you can move through the problems at a finishing pace. If one seems tricky, wordy, or hard, mark it and go back. Don't waste time.
Yes, destroyer questions are helpful. Are they too easy? No. The math section of the test is easy. The timed conditions is what is meant to get you. I always shoot for 100% and am surprised to find that I miss several.