Hi Chris,
100m / 300ft is the maximum spec for Ethernet links.. So for 300 meters you are better off with 2 fiber media converters.
Be aware that the boxes you suggest are with POE.. I don't have it by head if the IP units do support poe.. As normally 1 Gb links and poe run over the same wires.. So check this in the specs of the Teranex converters..
About the ubi's I do have a lot of Ubi's and expierience.. I do not have the Tico units.. So i can not talk from expierience.. I'm not entirely sure why it won't work.. Maybe it uses a jumbo frame or does it have some sync info going haywire by the packtising of the Ubi's..
Make sure you have Airmax enabled. This will normally ensure a better troughput of data in the Ubi's.
Make sure AC is enabled... But i guess you did a troughput test on them.. Also don't put them too close to eachother for testing They can suffer from packet loss if too close because they go blind on to much TX power..
And while i do think this will not make a difference.. But try to play with the bandwitdh of the link.. THe wider it is the more data it can handle.. But it takes more channel width and in RF crowded enviroments this can be an issue..
BTW IF Tico 4:1 compression on a 12Gb/s signal.. Try to send a 3G signal and check if this comes trough?! Less data and bandwitdh. Maybe better results..