Cartridges for rear of stage orchestral resolution

How about the Dynavector XX2 Mk2? Won't break the bank and I believe it has the kind of resolution you're looking for.

Opus88
Rsrex is correct in that back of hall imaging is usually a function of the speakers and room acoustics. Although of course if this information was not in the original signal, it would not be possible to reproduce it.

The other area which you need to look into, and perhaps should do first before investing in another component, is to make sure that the TT, phono/pre, power and speakers are rigidly supported. Also that your cables are elevated/isolated from ground borne vibrations.

Go to a concert, close your eyes and listen for depth...It's not going to be there.

I don't think you can conclusively say that all concert halls sound like this. This really depends on how the back wall of the concert hall was designed. Some which have lots of absorbing materials behind the players do not have this - mostly modern concert halls. OTOH there are those like the Vienna PO, Kingsway Hall (used in many older Decca pressings), where the hall acoustics are clearly audible and do give the sense of the venue.

Which is better? Well that's up to you. I find that some newer halls, with too much absorption, rob the performance of its dynamics and really kill the performance.

IMO the Benz cart should be able to reproduce these acoustic cues, so a better tubed phono should help. I also feel that a unipivot arm would serve you better in getting that detail, unfortunately that could blow your budget.