With a UHC filter and a 24.5mm Meade SWA eyepiece I have seen the horsehead many times in the 16" as a subtle darkening of the field if you knew where to look. Not worth writing home about
. A borrowed H-beta filter brought it out much better though. Sky conditions and how high it was also made a big difference. Something like Thor's Helmet or NGC3199 with an OIII is a much more spectacular object visually.
I would also add support to the idea that top modern wide field eyepieces with their multicoatings would only lose an imperceptible amount of light compared to those with less elements.