yes,
according many tests HNE is more accurate (than HEM)
when liquid fraction is close to 1.0,
HEM near bubble point (liquid fraction 1.0)
predicts a very low speed of sound (and critical mass flux)
while HNE introduces a correction for non-equilibrium,
there are many papers discussing this but
you can easily compare the two models from the Excel page
distributed with Prode Properties.
with Prode you can also evaluate the speed of sound
(in liquid and two phase flow) predicted by HEM at different fractions,
for a mixture of C3 0.3 C7 0.7 P 10 bar.a
liquid fraction 0.98 T 366.7 K , model Peng Robinson
the macro =StrMSS(1) returns 62.82 m/s
while at liquid fraction 0.5 T 432.7 K
the macro =StrMSS(1) returns 117.29 m/s
as reference the speed of sound predicted
by Peng Robinson at 10 Bar.a 364 K
for liquid phase is 543.79 m/s
hoping this helps.