I own several Vanguards and a Sentinel and am fairly impressed with the image quality and zoom.
These cameras use a CCD image sensor instead of the CMOS sensor the small xcams use, so the resolution is MUCH better.
One nice thing about these is you have the choice to run them either wireless or wired.
They don't have a mic so there is no audio, though.
I have several Vanguards placed inside my home in windows that watch the property as they are indoor cameras.
The Sentinel needs to be mounted very high up as its tilt is optimized to look downward, but gives the added benefit of including the outdoor dome to mount it outside.
I actually have a Vanguard in my Sentinels dome as the tilt was too limited on the Sentinel for my application.
This seems to work fine.
I have had issues with the gears on the P/T motors giving out and returned one camera for replacement, so an extended warranty may be worth looking at if you decide to purchase one of the cameras.
The cameras work fairly well in low light situations but the shutter speed needs to slow significantly to allow more light to enter the lense.
This can make the image fairly grainy in darker areas and appear as if things are in slow motion.
They do require much less light than other x10 cameras, though.
Hope this helps some Tom.