an excellent reason to use wifi indeed, would stop a cablemodem, or dsl modem spike in its tracks.... but if I'm not mistaken, most wifi routers are already pre-configured as you say, with up-link on the RJ-45 side & down-link on the wi-fi side... or am I missing something?
Perhaps you are missing a spike on the AC line?
WiFi will not negate the lightning hazard thru the AC.
A smart miner will have a surge protector AT the miner.
Surge protectors with telco, coax, and ethernet ports are common.
A UPS would be even better so you can mine thru brown/black outs.
You would need a very big UPS to mine for more than a few minutes during a blackout though.
Everything in the chain needs lightning/surge protection!
Miners will come to a screeching halt if your upstream equipment goes poof.
Even though I posted a link to a WiFi solution I do not advocate WiFi for mining.
There are security/reliability issues.
A spike on the AC line could damage or destroy the power supply to the miner and the power supply to the bridge but is less likely to destroy the miner if it does not have a Cat5 ethernet connection.
The problem I described earlier, the grounds cut on the roadside telephone poles, increase the chances of a high potential riding in on cable, destroying the TV and anything on an ethernet from the cable modem via energy finding its way to ground through the wall 120vac.
Surge protection is fine. I agree.
The security issue is an element, true. So is the slower connect rate. However the time lost to a machine being down that costs thousands of dollars, is an issue. Having seen melted copper of an RJ-45 connection personally, the loss of a KNC miner to lightening is worrisome. I don't own a $2000 TV but if I did I think I'd look into only using something like WDTV via wifi and not having the cable to the box. The greater threat is the potential between the cable and the AC power in neutral in the event of a lightening strike. At least that's what I gather from having autopsied a lightening fried laptop.