I did the exact same thing back in 2008, but with my GT. Loved every minute of EK9 ownership. But funnily enough I now have another GT.
I'd say go and test drive an ek9 first. They're not for everyone, especially if your coming from a well specced Glanza. The stock b16b has to be worked really hard to get the best out of it. But so rewarding when you do, and the handling is out of this world.
IMO....Get the ek9, sell the b16b and get a stock b18c4 or b16a and turbo it. Best of both worlds then.