pae kernel is so called because it use a particular feature of the CPU (Physical Address Extension), which allow for addressing up to 64Gb RAM,
although pae is present on all recent CPUs, is not available on all CPUs.
Other than the above, actually the differences are related to Kernel Interrupt time actually set to 100 Hz in pae version, and set to 1000 Hz in all other PCLinuxOS versions,
(an higher interrupt frequency allow for faster kernel reaction upon interrupts, may be useful for some applications that require realtime response),
other difference are related to the default scheduler (bfs vs. cfq), one version, a64, is optimized for AMD 64 bit CPUs.
The 512 Mb video-card memory, are unaffected by the kernel choice.
Unless you have specific reason to require bfs scheduler and 1000 Hz frequency, there are no drawbacks using pae kernels.