I am blessed to be able to conduct the University Orchestra for a section of each of their rehearsals this semester. Last Monday was my first time in front of them, and it was fantastic. There were (as always) several flubs but nothing that required me to stop the ensemble. I was able to keep them together by giving them rehearsal numbers and clear cues. I conducted the second movement of Dvorak's New World Symphony, number 9. It is beautiful music and I could feel that the musicians respected me and were giving their best effort to the reading. I feel the success I had is due to the amount of preparation I put in studying the score, as well as the time I've spent in conducting study over the past years working on instrumental technique as well as choral. A lot of conductors say there is no difference, and in the essential framework, or 'home base' of gestures, there isn't a real difference. Beyond that, however, I feel a distinct difference between directing instrumentalists and singers.
The biggest difference is in the amount of musical training. The average orchestral musician has been studying their instrument for at least a decade, if not more. Many of them have been playing for longer than I've been alive. Some twice that. The average singer may have been singing since they were young, but for most it is purely recreational, and coincides with little to no training in music reading, technique or expression.
So the first road block to me as a choral guy in front of an orchestra is that many of the people I am to lead have far more experience, knowledge and musicality than me.
The other big problem is that orchestral conductors on average are far more skilled than choral conductors. This is undeniable and directly tied to the number of orchestral and choral conductors in this country. Almost every church has a small volunteer choir, most schools have at least one if not several choirs, and most universities and colleges have between 2 and 10 choirs. Many schools have bands but not orchestras, the days where churches had orchestras attached to them are just about dead, and even large universities have at most 2 orchestras with 1 being the overwhelming majority. With so many fewer spots for conductors in the orchestral world, obviously the ones with positions will be more talented than the plethora of choral conductors in the country. Many church choirs are led by people with no more musical training than singing in choirs for a few years (one of my conducting students directed a church choir for 2 years while in high school, never having had any conducting training, and having sung in church choirs for several years).
I don't think this is a bad thing, as the more people we have actively engaged in music making instead of passively observing the better. What it does result in is the (correct) notion by instrumentalists that the average choral conductor is not as skilled as the average orchestral conductor. So my big roadblock here was knowing that a large portion of the ensemble will automatically be looking for me to be a poor conductor because I'm a vocal guy. This is also a possible advantage however, because when people assume you suck, it's relatively easy to impress them.
In the end it went very well, I had a large number of players come to me afterwards and compliment me, and I had several people tell me the best thing a choral guy in front of an orchestra can hear:
"You were clear and easy to follow"