I have the same problem with my R7000. Seeing good signal strenght with stock Netgear firmware and Merlin-Xvortex, but with Tomato it drops to the piont it can't get thru a sigle wall. Using Shibby 131.
I did some measurments with my lg G3 and app WiFi Analyzer and Fuke AirCheck. It showed severe signal strenght fluctuations. I posted my findings on Shibby's bug tracker but he treated my report as TRASH. Nice one Shibby. I cant tell signal is dropping 20dBm and rasing 20dBm again several times in a minute. Tested this on R7000 and rt-n16 and wrt54gl. All showed severe signal strengh fluctuations. With stock or merlin firmware signal is not fluctuating and has 10dBm more strenght. R7000 and tomato shibby 131arm is the same as rt-n16, exept 5g which is weaker than 2.4g, so no point posting more screens. But the signal fluctuations are the same. The mesurments done on Lg G3 are consistent with AirCheck so no point uploading them. wikidot want let me post a picture or a link because I have to low KARMA.