To quote a friend of mine who said his metabolism never returned to normal: "Weight gainer ruined my life"
After "bulking" I feel my "metabolism" was never the same. Could just be that I got older, but I doubt it. Pre-bulk, I never thought about food, ate whatever I wanted, and stayed super lean, maybe 7% or so.
After bulking and leaning out again, I feel just like an average gym goer. Leaner than most, but nothing special (maybe 10+%), despite being way stricter with diet and exercise.