This is an old post and I get that... but for others that come across this, if the consideration is an A 1031-U, then the best passive omni paddle on the market is the Wisycom ADB. 3.2dBi and typically sells less that the 1031.
However the user selecting the ADFA is even better; besides the improved passive gain like in the ADB, you get excellent DSP filters and active gain controllable from -12dBm to +27dBm. Its also a smart antenna that can be controlled via software.