The 802.11n products support 802.11g just like standard 802.11g routers, so you don't lose anything. A number of 802.11n products even support 802.11g MIMO. Suggesting that 802.11n hardware is inferior is a gross distortion, when the opposite is generally true. The 802.11n products almost always feature faster processors and more capable radios.
They didn't go cheap with the parts and they can be flashed with a variety of different firmwares depending on your taste.
Buffalo's 802.11g products provide excellent wireless coverage, and support DD-WRT, but to suggest they don't use cheap parts is inaccurate.
The Buffalo 802.11g products are based on the Broadcom
BCM5352, which is just about the cheapest SoC solution on the market for 802.11g networking. Solutions based on that chip don't even use a dedicated ethernet switch controller, as it is integrated and shares the same cpu. Broadcom itself advertises this solution for routers with "the lowest bill of materials cost in the industry."
The only area where 802.11g products "outperform" most 802.11n products is in DD-WRT compatibility. DD-WRT still doesn't fully support the next-generation chipsets (with superior performance) found in most 802.11n routers. As one example, compare the specifications on the Broadcom
BCM5352 for low-cost 802.11g routers to the Broadcom
BCM4705 intended for 802.11n routers.
Once DD-WRT fully supports next-generation chips like the BCM4705, nobody will be buying those older and much slower BCM5352-based solutions, except those looking to spend under $50 on a router. I agree there is a demand for low-cost routers, but this isn't Fatwallet.com; this is Anandtech where some members spent $500 on a quad-core Intel cpu, $50-$75 on a heatsink (or $150+ on a watercooling setup), $300-$600 on a graphics card, plus hundreds of dollars on case mods.