Matthew Caulfield has hit the nail on the head.  The Wurlitzer trumpets
simply (for the most part) duplicate the melody for emphasis, as
required, and when used so make the worst use possible of the musical
scale.  They are not a counter-melody.

Many years ago I purchased a number of Wurlitzer Style 125 rolls from
Play-Rite with the intention of building a small fair organ, but when
I checked out the actual arrangements I decided that I would not proceed.
There is little, or no, counter-melody, which can be confirmed by
listening to recordings of such instruments.  Indeed, the W 150 scale
is even worse with only three basses and duplicated trombones.

In comparison, the European organs with counter-melody use this division
intelligently, as described by Hans van Oost.

One only has to listen to a Ruth 33 to understand the world of
difference to a W 150.  Both these organs have a similar number of
notes on the scale, but the Europeans knew how to arrange with trumpets.
Indeed, I could go further and say that the Germans were the only ones
who knew.  Gavioli and Limonaire used them as a register, activated by
a key unlike the wasteful Wurlitzer method, whereas Ruth, Bruder and
other Germans used them for melody accentuation, accompaniment, etc.
It is difficult to describe.  You really have to listen.

In a small organ you really don't need a counter-melody, however it is
used.  Compare the small Wlihelm Bruder Söhne Model 77, with only 37
notes, to the W 125 with its 41 notes.  I could listen to the first all
day but would be bored by the second after a couple of tunes.  Similarly
check out the WBS Model 78 with its 41 notes.

The only decent arrangements I have heard on a small Wurlitzer are
those done by Art Reblitz.

People really should broaden their horizons and look beyond the
Wurlitzers.  There's a lot of excellent music out there.

All the best from the UK,
Nicholas Simons