Yes, typically home routers tend to use pretty industry standard chips like Broadcom chips (like the BCM5357 in my home router). D-Link, Linksys, and crew don't usually roll their own SoCs, but just seem to throw off the shelf stuff in there. These chips tend to be SoCs, and while I can't be totally sure that there isn't a weirdo NSA backdoor on it (probably just as likely as any other router, residential or commercial), most of the meat lives in the chip, and with good open source firmware (DD-WRT et al.) it's probably just about as reasonable as anything else coming and going. I certainly have far more faith in a regular off-the-shelf SoC + open source firmware tuned to my own needs (and believe or not thisn't hard at all) than anything with propriety firmware, including (and especially, to me) Apple. Maybe the next best thing to do is to build your own WiFi router from totally off the shelf parts (not so hard to get into a small form factor any more).

As to inspecting the SoC itself, that would be certainly interesting. Most of them are just ARM SoCs; this might make for an interesting blog post looking at the silicon.