lemonpeel will almost for sure munch down on your corals.
i saw the most sorry reef display in a city public aquarium, oh say 12 or 13 years ago, that appeared absolutely decimated and barren.
i wont say which one to save embarrassment but it looked like a barren riverbed instead of a reef display. they even had pics proudly posted of their equipment room around the display...needless to say, even for that time period...was a demonstration of a large budget with no knowledge of what to do...
anyway, back to the display...amid this barren live rock, i see a fish pop out! guess what fish? yep, a lemon peel angel!
i just looked at it in horror at it being in a 'reef' tank. i then heard an employee standing next to me (noticing me looking at the fish intensely) and said 'yeah, we are trying to get that guy out'. of course, i felt like saying 'man, he shouldnt have been put in there to start with!'
as for pygmy angels in a reef tank?
they are definitely hit and miss.
i have a multicolor in my sps with some lps. she nipped all my clams to death (one being an 8" maxima) and likes to take a bite out of my scoly's every so often...other than that, she doesnt do much else. but, like i said...every angel is different.