Setting Nstreme with a 70% CCQ slightly improves my throughput but latency is through the roof. It would reach around 1000ms. Switching to Nv2 drops latency to ~40ms but my throughput also drops significantly, even lower than 802.11. Just like what 0ldman said using nstreme and nv2 protocols probably requires a clean link to be optimal.
Have you tried changing your frame limiter on nstreme?
In high noise I've found 2000 to work better than anything else, type is best fit. Yours may need a different limit, but that works for me.
Ste, you have better bandwidth with 802.11? I typically find the AP stuck below 10Mbps on 10Mhz channels without any of the polling protocols, usually double that with nv2 or nstreme. My old backhaul maxed out at around 35Mbps in turbo A 802.11, got a little over 50Mbps with nv2.