Hi, I own 2 beeper collars, both by Dogtra (the older 2000 T&B and the new 2500 T&B). I much prefer the 2000 T&B, the beeper in on the top of the dog and IMO louder. These collars have been the best I've ever owned, not one problem and reliable as all get out. Can't say about the other brands of beeper collars.
With these collars you can run them were they will beep every 6 to 8 seconds or on point only mode (beeps every 2 second while the dog is on point or still). They also have a locate button. When you push this button it will beep only once or as many times as you press the button.
As to spooking the birds, not been a problem at all. I only hunt wild birds and can't recall when the birds flushed when the beeper was going off. In fact, it seems to hold them better, don't know why, just my experience.
I'm a big fan of beeper collars and won't hunt without them.
Good luck!
Greg