allpass filter in EngineersFilter?

[DJ Saint-Hubert]

just curious in particular, if an allpass Bessel filter would do what I suspect or not, that is, give a much smaller 'nudge' to the phase than a conventional allpass? Google tells me bessel allpass filters exist somewhere at least. Also wondering what a chebyshev allpass filter would sound like, probably nothing useful for cleaning up sounds but might make an interesting effect