That link didn't work for some reason.
http://downtownaustinblog.org/2013/1...unit-highrise/
Assuming that the floor to height ratio is the same for the Four Seasons Residences nextdoor, 99 Trinity Tower should be around 465 to the main roof and about 488 to the mechanical penthouse. That would make it taller than the W Hotel & Residences which would make it our 4th tallest.
Four Seasons Residences is still one of my least favorite new buildings, so whatever can be built next to it to steal some of its thunder is fine by me.