You'll be much happier with the EM50 then the EM25. ALthough the EM50 is discontinued, the EM25 does not replace it.
Starkeeper

Well, Star, but if EM-50 has an accompaniment/lower (up/down/off) volume control
-is accompaniment AND lower (all the time together, no possible to regulate separately both) or is "accompaniment OR lower" and then, is possible a separate regulation? For example, is it possible mute accompaniment but not lower?

ACC parts/Lower up down button:

for ACC parts when Arranger modo
for Lower when Organ modo

Lower voice can not use in Arranger modo.


Upper 1/2 button:

select 1 or 2 with other button


My opinion for EM-50:

Good option as Style Player
Not so good for Pro musician performing use.

Sound Quality= Good with external audio System. Internal is weak.

Effect= Reverv, Chorus only

It is a pity lower voice can not use in arranger mode in EM-50.
Old Rolands kb (E series) can use lower in arranger mode.
Why modern Rolands can't?
What kind of progress is it?

I don't know of ANY modern arranger that can do this (play lower voice along with arranger). Yamaha has a full keyboard mode that will play the arranger, but that is with one voice over the full keyboard not split/organ mode.
Starkeeper

Just program a pad into a user created style.
Starkeeper