I concur- I've a copy of the "Speccie" crossword book and dip into it occasionally, and the standard is usually somewhere in the region of "fiendish". There are several "Doc" puzzles in there and they are generally superb with really interesting themes.
I started doing the "Speccie" about eight years ago having been a DT "Back pager" for three decades, and at first I found them to be really difficult and sometimes impossible, but then I learned of "Chambers Crossword Dictionary" and that made things easier. I won first prize once....
However, I'd say that during the last three years they have become generally much, much easier and it's not simply down to me getting better. Yesterday's "Doc" was a walk in the park- even with a filthy hangover from the previous night's excesses with a couple of old school chums I still managed to solve it in record time, having guessed the theme from 23A and twigged to the pun in the title.