When using a TNA-301 as the AP, and a TNA-302 as a station, you should be able to achieve an MCS 12 (16QAM) datarate when the link distance is ~210m on channels 5-6. You can still achieve MCS 12 on the lower channels for distances up to ~180m.
Your speeds at this modulation will be limited by the 2.5G ethernet port, and maxed out at 2.3 Gbps.
Once you go longer distances, the MCS9 modulation will still allow you to achieve ~1.9 Gbps (TCP) for up to 800m. And links can always be made up to 1350m, using the lowest modulation, MCS1, on the upper channels.
These numbers came from the Tachyon Link Calculator, which you can use to help design your Tachyon-powered network.