The 16VT brakes aren't that bad, I have tracked my car on them and they last well with uprated pagid pads and 250bhp+
While I never have owned a 20vt i have read on here the 16vt brakes are up there with the brembos if they are in good condition.
In saying that I have now swapped the brakes to 330mm brembos
To change the 16VT brakes isn't that straight forward (ie the 20vt brembos don't bolt up without other parts, I would say get some different pads and rotors in there and they will be pretty good, in saying that you can never have too much stopping power.
You pay your money..... but I got decent pads etc and then did new wishbones and shocks/springs before I went to bigger brakes