For validating the code, the proof would be in the pudding. I've tried to get Speaker workshop going for a while now. Just purchased another soundcard, the EMU 4040 and it seems to be responding better. But I have a standard setup with a scope, freq counter, sig gen, volt and current meter for backup readings. I have not tried any of the other products out there yet, although I do have many down loaded.
I've just finished a room in my shop for the sole purpose of electronics, by this time next week I should be able to tell you how well speaker work shop compares to my fixed readings. The thing I like about speaker workshop so far is that once you begin to understand what it is trying to do, then you can make adjustments on your end to get more acurate results, that and the fact that it is free.