Choice of chipset

I am trying to decide between two radio bridges for client mode.

Both radios are from same vendor.

Model X has conexant / intersil Prism 2.5 chipset but has had occasional firmware and other complaints from users. Said by one company rep. to be better in range than model Y. 200mw transmit output, 95dBm receive at

1Mbs

Model Y has Realtek RTL8186 SoC chipset and is new to market, firmware either new or recently revised. 400mw transmit power, 92dBm receive at

1Mbs.

Both have 8dbi integrated panel antennas 35 degree horizontal and vertical spread.

My main AP is 2/5 mile away, near line of sight, 90 degrees to the side of the primary vector of the signal which is pointed in a downward tilt to cover an immediate two block area. My line of sight window is about

45 degrees vertical by 100 degrees horizontal, so I'm capturing only the portion of the signal at right angle to it and within that window. Several other AP choices at further distance to be determined if I ever get it mast mounted with a rotator.

So far I have had to return an 85mw radio that could only get a stable connection about 20% of the time with a small whip antenna (5dbi?), due in part, I think, to some waving tree branches that partially obstruct.

What is your best guess as to which model, X or Y I should try next? In talking to one mfg. rep. he states firmware is better on model Y, but this is a new model with a fairly new chipset. I also need something that will be compatible with a wide range of OS's and utility software, which speaks better for model X (prism). What do you think?