While in the office, download speeds were about on par, the E4200's performance outdistanced the Westell 7500 as I moved farther away (see table below). Performance was 28% faster 25 feet away in the family room and 74% faster in the kitchen, located just below the family room on the first floor; and 169% faster in the first-floor living room, some 50 feet and several walls away.
Throughput for the E4200 dropped only slightly, to 13.33 Mbps, while the Westell tanked at just 4.96 Mbps.
It's clear that the E4200 delivers sustained higher bandwidth consistently over a longer range than the 802.11g-class Westell unit
That said, results on individual tests varied widely with both units, and in each case the routers struggled to provide consistent bandwidth to the master bedroom on the second floor (although in the end the E4200 posted better averages overall). At one point, the E4200 averaged a download speed of 9.88 Mbps. During another set of tests performed at a different time, performance dropped to just 1.18 Mbps. (I'm reporting the overall average.) On the ping test, average latency was much better with the E4200, at 68 milliseconds, versus a whopping 109 ms for the Westell unit. On the iPad, latency surged to 350 ms. More on that in a minute.
It's impossible to say what caused throughput to vary so dramatically from one test time to another. Cisco's own test software measures performance with the E42400 posted similar results. It's possible that the performance drop was caused by my ISP, Internet traffic or server delays or other issues on the other side of the router. Another possible cause may have been intermittent radio frequency interference from another device inside the house, or possibly from the street, as the master bedroom is in the front of the house and adjacent buildings are very close.
My bandwidth mileage also varied depending on the device I was using to connect. The Speedtest app for the iPad turned in results that started at about 7 Mbps in the office, kitchen and family room -- about half of what I achieved using the MacBook -- and degraded to under 3 Mbps in the more distant living room and master bedroom -- not optimal for streaming video. (According to Cisco, the standard for video streaming is 22 Mbps, although I am able to stream video just fine on much lower bandwidth).
To get to the bottom of this, I brought both the iPad and MacBook into the family room and repeated the tests, alternating between the two devices. During one session the iPad posted an average downlink speed of 1.77 Mbps while the MacBook averaged 14.89 Mbps. At other times, however, the iPad posted scores in the 6-7 Mbps range.
Finally, the integrated wireless feature of our recently acquired Vizio VBR210 Blu-Ray player had trouble consistently connect to the Westell or Linksys routers. When it did connect, it had trouble maintaining the connection, or the picture would periodically freeze or break up. Testing on the laptop in this location seemed to confirm that sufficient bandwidth was available, and the Roku box, moved up from the kitchen, worked just fine in this location as well. I continue to work on the issue with Vizo and may need to replace the unit.
The point here is that even a high-end wireless router has its limits: You may still have dead spots in the house, in which case you may need to buy a range extender (a radio-to-radio signal booster/repeater) or hardwire bandwidth-hungry devices such as a Roku video streaming appliance back to one of the E4200's four gigabit Ethernet ports.
Cisco hasn't yet introduced a range extender compatible with the Linksys 4200, but a spokesperson says it should be available soon.
In the real world -- in your home -- a new router may not solve all of your problems for all of your devices. Be prepared to do more than just swap out your router when troubleshooting wireless issues.
But a high performance router is a good place to start, and while the price is on the higher end of the spectrum, so is its performance. The Cisco Linksys E4200 is certainly a good choice.