As far as I know, the Tyros5 uses the same great feeling semi-weighted FSX keyboard action, with velocity sensitivity and aftertouch, as Tyros2/3/4,
This FSX action was especially developed and used to provide better control of Yamaha's new SA/SA2 sounds.
The original Tyros did not have this FSX action; it was first introduced on the Tyros2.
The FSX action is also used on Yamaha's 61 and 76 key versions of the Motif XF, and the earlier Motif XS.
I believe you will find the Yamaha action comparable to what is used on the Korg PA3X.
The best action, in my opinion, for playing piano sounds, is an 88-note graded hammer weighted action keyboard, but for arranger playing purposes, the semi-weighted action works fine, and is better suited for playing the instrument's other sounds (strings, organ, brass, guitar etc.) than the weighted version.
Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.