Is it possible to get the entire Photo Stream in my Aperture library? On my iOS devices, I see how many photos are in the stream.
The Photo Stream may be different for each of your devices, depending on when you enabled the stream on each device.
When you enable the Photo Stream in Aperture, it can only download what it still in iCloud, max. what has been added to the stream during the last month and max. 1000 photos. Your other devices may see older photos, because they downloaded them while they were still in iCloud.
See this document:
This may also be helpful:
To transfer the older Photo Stream photos, save them to the Camera Roll on your IOS devices and import them directly from your device, by connecting the device to uSB.