?First of all my “live room” isn't all that big to begin with. 10'x12'x8'. So in some ways it's not much bigger than some big studio vocal booths. Of course, there are vocal booths are are much smaller than that! So, maybe the fact that I already have a small room is reason enough to not need a vocal booth.

Either way, the size of my room now is comfortable. It's certainly not spacious, but it is cozy. People don't feel too enclosed while singing in it. To me, the most important thing is providing a space where the singer can open up. I want them to feel comfortable doing what they do.

From an engineering standpoint, I can get anything I want with a few sheets of rockwool, blankets, and a few mic stands. I don't need to a special vocal booth for this. I like being able to get flexible with vocal tone, if needed. A vocal booth is stuck that way for better or worse. It's very easy to knock down reflections in a live room. You can see pictures of what we did at the Micheal Wagner Workshop.

Price is another consideration. For the price of a vocal booth that won't get used all that often, I can buy a high end microphone, preamp, or compressor. Actually, for that kind of money I can take a vacation or go on a cruise or something.?

Conclusion

There are certainly benefits to using vocal booths sometimes. If the singer likes a vocal booth, get him / her a vocal booth. If you need lots of isolation because you are tracking live vocals, you'll need a vocal booth. However, that's about the extent of it.