The article only showed that 64 USERSPACE is faster!!! You gain absolutely nothing with 32 bit userspace!
Also the article is not completely optimal for compareing as ubuntu uses different CONFIG_HZ settings for generic/server and 32 vs 64 bit kernels. Basically you need a kernel with 100% the same settings.
Ubuntu is not a performance oriented distro. It is a distro that is supposed to be user friendly for people that don't know how to maintain/use a linux system or don't want to be bothered by doing so. Right now the friendliest and most trouble free version of linux on x86 is 32 bit. Canonical isn't likely to change their recommendation to use the 32 bit version any time soon no matter what the performance numbers look like.
As anybody can see, on average there is actually slight improvment in terms of performance on PAE-enabled systems. But I would attribute this to the fact that system have then a bigger filesystem cache. To really show how it affects perfrormance, one would need to perform tests on 2GB system. Anyway, nice it works good, especially, as I use PAE because of Xen.
Yes, Nexuiz does include 64-bit binaries.
I know ubuntu targets newbies but people who are likely going to try ubuntu arenít going to be xenophobes. Their going to have some understanding as to what 32 and 64 bit are and assume that if ubuntu is recommending 32 bit its going to suffer 64 bit issue on the scale windows did.