Bob, You are the best. Your test is much appreciated.
It's really strange though. Which SigmaStudio version are you using?
I'm running 3.11 Build 2, Rev 1396 (9/8/2014) and the limiter does not limit at all for me.
So basically the limiter block in the version above is completely useless.
By the way, according to your first screenshot, the output should be limited to ~0.3 (-10dB) instead of 0.5 (-6dB), so your version is not okay either.
Dear fellow AD engineers, if you are reading this, please address this issue.
A limiter is a pretty important and basic element.
FIR Filter: sure, we can use the full range. I was thinking of getting rid of the necessity of coefficient normalization (and output level adjustment), since most FIR designers calculate fixed point filters in 0.32 format.