Apparently the rest you do not understand how Android and the underlying Linux kernel operates.
So you don't think it's odd that a new Android firmware suddenly needs 200MB (in my case) more than the previous version ?? Just because it's newer and uses a newer Linux kernel, it's perfectly alright to take all that extra memory ? After a fresh start with no extra apps loaded ...
The change log only mentions Android being upgraded from 4.0.3 to 4.0.4, a new wi-fi driver and a load of media center (which I do not even use) changes ...
No, I do not think it odd at all for the RAM usage to go up in any new first release of a new OS (especially with how Archos tends to screw things up the first time around). In fact I would actually have expected an increase in RAM usage (even if Archos didn't screw a few things up).
Efficiency of an OS is not about lowering RAM usage. In fact, it's completely the opposite. The more efficient an OS becomes the more things it can have using RAM at any given time. Every newer OS tends to always require higher system resources anyway. ICS (Android 4.0.3, even after Archos fixed and tweaked things) still uses more RAM than Honeycomb (Android 3.2) did. I would therefor expect Android 4.0.4 to then also use even more RAM than 4.0.3.
Since RAM usage is dynamically controlled by the OS it really doesn't matter to me at all as long as the OS works correctly.
I'm not sure just what you were trying to go to about the change log. That only lists the main things that people would mostly likely notice being different. It does NOT include the hundreds of driver changes or other modifications that Archos has to make to get Android and their own extra apps to run on their specific hardware. Nor does it list the over 100 changes and bug fixes that Google made to the OS from 4.0.3 to 4.0.4.
Most of what is listed in the change log is fluff about new features to the Archos media apps. I could care less about that (although nice of them to add new features). The ONLY REAL IMPORTANT line in the change log is the very first line about changing to the Android 4.0.4 base. That's a really huge change under the hood... especially with Archos actually jumping way ahead several Linux kernel versions (that is not really required to run 4.0.4).
Although Archos does not come right out and say, the whole real purpose of this upgrade (especially the big jump in the kernel version) is all about getting the G9 devices ready so that they can (possibly) be upgraded to Jelly Bean sometime next year. Between now and then there will likely be many more updates to fix bugs and may add a few more features.
In other words, if Archos can not get this upgrade to work on all the G9's (with all the hardware changes they made in them in the last year)... well, then there would be no chance of ever getting a Jelly Bean upgrade in the future. As such, to me, there are far more important things to worry about than RAM usage (which I consider totally un-important because the OS takes care of that by itself... if the OS is working correctly anyway).