Guy I work with got his tonsils out when he was in his 30's. From his account of it... it is, indeed, as bad as they say it is. Holy hell. But then again, he didn't like the way the pain meds made him loopy so he did without. I imagine it's manageable with meds. Maybe?
Just as an aside... getting tonsils out later in life is seemingly nowhere near as bad as getting circumsized later in life- according to a 1st person account of it from another dude at work.