I have three different routers running DD-WRT (I couldn't manage to find usable packages of the other three firmwares you mention). Of those, one is running kernel 3.2.12, one is running 2.6.34, and one is running 2.4.37. I know for a fact that the one running 3.2.12 (firmware build 2012) is never going to be updated, as newer builds are larger and do not fit in the router's flash. The others are in a similar situation, with their builds not having been updated since 2011 and 2010 respectively.
I appreciate what the DD-WRT people are doing, but I would hardly hold them up as the paragon of updated, secure firmwares.
I have this exact same problem. I used to run an Asus Router with DD-WRT and it was awesome.
However, the firmware version I needed never got updated again for whatever reason. Along with the barrier to contribute back to the DD-WRT project I moved on.
Are any other Firmware versions out there more actively maintained?
OpenWRT seems to be fairly well maintained but I haven't used it long enough to have run into devices being dropped. It doesn't have as wide a range of support to begin with either from what I understand. I've heard lots of good things about tomato that way also but it doesn't support the devices I have.
I think OpenWRT's hardware support is limited primarily by the availability of open-source drivers. They'll ship proprietary firmware where necessary, but proprietary drivers prevent them from updating the kernel at will.
One of my spare routers (came free with purchase of a cable modem) has only 4MB of flash storage, and recent builds of OpenWRT have had to strip out the web interface but in exchange gained IPv6 support. It's also got only a 350MHz MIPS 24k processor, so it's too slow for serious use with any connection faster than ADSL2. There's a lot of router hardware out there that's just not up to the task of being a home gateway anymore.
It's down to the binary drivers. They lock firmwares to a specific kernel.
Your only option is to backport fixes. I read in forums that devs aren't interested do to introducing bugs and citing lack of free time. I roll my own Tomato kernel but I've only included a couple backports.
x86 is really your best bet as an enthusiast. I'm waiting for Braswell hw, personally.
No need to compile your own kernel, or get a huge x86 board. You can use an Atheros-based TP-Link router with 100% free software, bootloader and firmware included. There's no reason you can't update this.
Now you've doubled your RAM requirements, because all but the newest consumer routers use NOR flash and can directly execute code from the flash without having to copy it to RAM first. If you have to start using RAM to hold code and static data in addition to transient stuff, you're going to need to bump up a size and that's going to ruin the profit margins on all the dirt-cheap low-end routers out there.
I appreciate what the DD-WRT people are doing, but I would hardly hold them up as the paragon of updated, secure firmwares.