Security mode throughput
The pattern of wireless security mode throughput loss in draft 11n products is pretty well established at this point. Belkin makes no apologies about the low throughput when using WEP or WPA/TKIP security and even reports a 54 Mbps link rate ("Speed") in the wireless adapter's Win XP Local Area Connection Status window in both those modes.
Figure 11, taken running uplink in 20 MHz channel mode, shows a loss of 71% and 75% for WEP and WPA-TKIP modes and about a 10% loss for WPA2.
Figure 11: Security mode throughput comparison - uplink
Figure 12 shows downlink loss for WEP 128 and WPA-TKIP around 63% and no measurable loss for WPA2. Once again, the lesson here, is to use WPA2 security or face a severe throughput hit.
Figure 12: Security mode throughput comparison - downlink
Throughput vs. Path Loss
NOTE: We don't refer to "range" in these plots, but instead use the more accurate "Path Loss". For an explanation, see the How we Test Wireless article.
Figure 13 was generated using the Compare Benchmarks tool of our Wireless Charts and shows up and downlink performance in 20 and 40 MHz channel modes. The plots show that 40 MHz mode throughput is better than 20 MHz mode both uplink and downlink at lower path losses (stronger signal level), but crosses under the 20 MHz mode lines as path loss increases.
Figure 13: Throughput vs. Path Loss
If you look at the average of these curves, as we do in the Average Throughput Wireless Charts, the Vision does pretty well, ranking in the Top 5 for all four modes.