Thiel Owners

I can offer a general answer. For perspective, the difference between 33 and 35 Hz is barely academic, virtually identical. Thinking in half-octaves (15 Hz at 30 Hz) is more germane to performance class than is a few cycles. Low E1 on a bass is 40 Hz.

Differences are accounted for by technical particulars. Bass alignment is very specific to cabinet volume, rigidity, driver position, diaphragm mass, maximum excursion, suspension characteristics and motor factors. An alignment is optimized considering these many factors among others. 

Not much musical content below 35 Hz: 

http://www.sineworld.com/html/basic_knowledge/freqchart.html

I can never again live with a speaker that isn’t robust down to 40 but I’d rather have a killer speaker that stopped at 40 than a mediocre one with full output below 30.

Tomthiel, does the 3.5's eq do anything besides bass boost?

Beetlemania, true but the auditory value of extended bass garners greater perceived value. Of course, if one's room can't accommodate those waves things can go south.

The Absolute Sound basically asked the question when having reviewed
both the 3.7 and the 2.7 , is 2hz worth almost twice the price ?
So Tom's point about the difference is academic but
The auditory value of extended bass might not be heard ,
but the feeling  can be quite rewarding  .