The Growler/mini comparisom is an interesting one. I also thought the Growlers had more low end when listening to them.
The interesting thing is when you look at the measured responses. Part of what your ear hears is relationships, not so much absolutes.
Yes the Growlers had a little (1 1/2dB or so) more low freq below 50Hz than the minis did. But above 55Hz the minis were that much or more louder (up to about 110hz).
But the ratio of the lower response (below 50Hz)to the upper response 50-100hz is greater with the minis, making the growlers seem to a much greater low freq output than they actually have-in relation to the minis, because of the lower upper bass output.
Is this good or bad-it just depends? Our ears are falling off in response at this point, so the extra bump may be good-maybe not, it just depends on where you need louder output-above or below 50Hz.
As always when choosing subs, a person has to take into account all the issues including sound quality (with low freq extension), sound quantity (sensitivity and power handling), size, price, fit/finish etc.
Different people need different needs-there is no one size fits all.
That is why events like this that allow people to hear/see a good variety of subs together and in various combinations are useful.
And the only way a person can judge for themselves is to be there.
Only so much can be gathered by looking at spec sheets (if enough proper data is supplied on it-not just numbers)-the ear is the final judge.
EDIT-clarity