TrueGigabit would help if your wired network devices had gigabit ethernet hardware in them. This would be for instance if you had a wired network with computers that had gigabit ethernet cards in them and a network attached storage device also with gigabit capability on the wired network, then you would have super fast backup.
Gigabit also refers to bandwidth: if you have 10 computers streaming 100 Mbps each, you now have 1 Gbps streaming through the router.