I think WPA 2 support was added with 10.4.7, around the time of the mid-2007 Alu iMacs which was the last model to have Tiger pre-installed and Apple launched their Gigabit Airport Extreme. Around this time period Apple required WPA/WPA2 as default when setting up any Airport Extreme network with their Airport Utility.
The only technical problem I can think of with an updated install of Tiger is the workplace is running the same network name for both G & N networks which is problematic with some chipsets/devices, experienced this once with a friends ASUS AC1200 network as it would randomly disconnect... I was stuck using a cheap USB "N" adapter. In my experience during the PPC era many routers with the exception of Linksys WRT-54G/GL had lousy compatibility between chipset makers which lead to consumers preferring certain router models using Broadcom chipsets, even today some ASUS/Netgear/TP-Link/TrendNet models have issues with certain Apple iOS devices and a few Qualcomm multi-wireless chipsets(an older Snapdragon dual-core CPU and a more recent quad-core model).