That's tragic. I just picked up a Netgear WNDR4300 (openbox on sale at the local Fry's) to see if I could hack up a CeroWrt clone on it. It seems to be mostly the same hardware as the WNDR3700v4 and the TP-Link WDR43[01]0, with things just wired up slightly differently.
I'd be interested in your netperf testing setup. With the AR71xx chips going out of style, the AR934x series is probably our best bet for readily consumer-available hardware with open-source friendly SoCs. (Maybe a Xilinx Zynq-based router funded through Kickstarter? =)
This is all pretty new stuff, perhaps some more performance can be gleaned by tuning the compiler optimizations (-march=74Kc?), and perhaps the AR8327N switch chip could use someone poking about its driver (the rtl8366s in the WNDR3800 _has_ been around a while). Although, in all honesty, the omission of that second ethernet port could just be a coffin nail.
Helpfully, the WNDR4300 has 128MB of NAND flash, as does the WNDR3700v4. So compiling a full CeroWRT distribution shouldn't be a problem. The fixeth script will need to be changed, but not much else.
Lance
PS: I apologize if this post doesn't show up where it should. I joined the list to respond to this email, as such I naturally didn't receive the original..