Volunteers are crucial, no doubt about it. Start up churches probably require a much higher ratio of volunteers to attendees than a more established church with a large paid staff. ESPECIALLY portable churches. I don’t think this is a bad thing, in fact I believe that high volunteer ratio church can be very effective, because it frees up money for making more of an impact in the community. There is a major pitfall, though.
We recently ran a service at a new location that we’ve only been at for a few months. The day before the service I got a call from our sound guy for that service that he had a family emergency, and wouldn’t be able to make it. I wasn’t too worried about it though, because we have a couple of other sound volunteers who run other services who might be able to jump in, and worst case scenario, I could run sound. We got to the location a little earlier for set up, and the pinch-hitter sound guy showed up. But we suddenly realized we had a HUGE problem. The sound board had NO labels. Zero. Zip. Nada. All those channels, and no way of telling what instrument/mic was assigned to which channel. Regular sound guy had run this service long enough that he had all the channels memorized, but last-minute sound guy was lost at sea.

The biggest pitfall with relying on volunteers is allowing a single volunteer to take on too much responsibility. It’s SO easy to do, and oftentimes the good volunteers want to take the lionshare of the work. But replication is VITAL to the life of the church, more than just getting extra volunteers.
The number one thing to teach a volunteer is how to do the job with excellence. But as soon as they’ve got that down, the number two thing to teach them is to duplicate themselves. And YOUR job as the volunteer manager is to number one, make them feel appreciated for their time and skills, and number two, make sure they’re not taking on too much, and that they have someone they’re training up in their job.