Although this is an older discussion just some additional thoughts as I have been thinking about this as well...
Please note that I am NOT a professional anymore - which means I basically do what I want and what I like in trombone playing.
My current orchestral tenor is a replica of a historical German trombone - conical bore, large bell (regular tenor mutes are too small), no valve and no tuning slide.
I love the sound and response, tuning in itself is surprisingly good. It's probably as close to a German trombone as you can get. The sound is very very lively and adaptable.
However it does lack some flexibility due to the missing valve and is overall not the easiest trombone to play due to the missing tuning slide and being quite front-heavy.
Also as a sidenote it does not work at all with typical American mouthpieces, but very well with special German mouthpieces (playing a Klier Gössling moouthpiece on it).
I wouldn't worry at all about using it in any orchestral playing that I still do. It's normally not too demanding and also does not have many surprises. So the missing valve and tuning slide can be easily compensated and it's all about the sound.
But thinking about e.g. brass ensemble gigs - where the sound would also be great - I would be a bit nervous about using it. Anything that requires more notes to be played than typical orchestral charts, parts that have quick passages in the lower range and also potentially more sight-reading just isn't where I would feel comfortable with this trombone.
Therefor - as soon as budget allows it again - I will probably get a typical American tenor with f attachment again.
Quite possibly an 88h - or one of the old and good Blessing copies if I can find one.
Of course I could also get a German trombone with attachment, however I have a Kruspe with attachment available from a friend if needed and also the American tenor would just be even more variation to my collection
Markus Starke
https://www.mst-studio-mouthpieces.com/
Alto: Conn 35h, Kanstul, Weril
Tenor: 2x Conn 6h, Blessing medium, Elkhart 88H, 88HT, Greenhoe 88HT, Heckel, Piering replica
Bass: Conn 112h/62h, Greenhoe TIS, Conn 60h/"62h"