I have an M2 eggbeater on the roof of my house. I have it installed with the "ground plane radials" so it is good from about 65 degrees and up. Basically the opposite of what Bob Bruninga recommends. As one might expect it works for downloading telemetry from satellites that are at about 65 degrees elevation and up. I do also use it on the APRS satellites (NO-84 and ISS) for minimal QSOs with moderate success. I do not have a preamp attached.
Bob is correct about eggbeaters vs. verticals and elevation. When I was first starting with the birds I decided to try to get the birds at higher elevations so I set it up that way and it's still that way. I know I'm missing out on the low passes, but I'm OK with that for now.
For the voice birds (mostly SO-50 and AO-92) I use a handheld Arrow antenna and two Baofeng handhelds.
I'm cheap but I have fun.
Steve AI9IN