That's right about the Pioneer, 5 channels, 2 of which can be dedicated to Zone B, but the same source is always sent to both.
The disadvantage in moving the Pioneer upstairs for the Algonquins/M22s is that the only way to turn Zone A and Zone B off and on is on the unit itself, which would be very inconvenient for outdoor listening. (invariably we'd forget to turn off Zone B on the unit and my wife would be blaring Oprah over our Algonquins to the neighbor's dismay).
Based on what you said about eBay though... $100 for a secondary stereo receiver is about what I should expect to spend, so the Sherwood I mentioned might be a good solution.
