In short: reaching your goal (50Mbps) will be hard.
omniTIK is a 802.11 a/n device operating on 5GHz. High band means shorter range athough relatively high gain antennae help somehow. Realistically it is possible to reach up to 1/2 of theoretical throughput (300 Mbps for omnitik) in next to ideal radio conditions (no external interference, short to medium range between devices, etc.).
If single node serves as a hop (as is lower left node on your diagram), then same packet from left to right flies twice over the air, consumes twice the airtime. Further if not all devices in the mesh can hear each other, possibility for collisions increases (search for "hidden station problem").
All the mentioned problems mean that realistic throughput of such a mesh could be as low as one tenth of theoretical maximum. If one uses dedicated devices per link and assuming 5GHz band is used, it is possible to build a series of independent point to point links which will each run to its maximum speed (probably 100Mbps or higher real throughput). Or go for ultimate performance with
60 GHz family of products.