Should I be able to hear a 4Hz difference in my speakers?

How old are/were the Hawks vs the Forests?  

My Forests (not Signatures) took a long time for bass to come in.  If the Forests are new vs the Hawks being well-used, I can readily believe it's hard to hear a difference in their bass output (yet).

You probably need a very beefy high power high current amp into the little Totem’s to have any chance of much that can be heard happening at 28hz. Most amps will probably say uncle first. If the room is smaller rather than larger, that will also help greatly. Those little guys have to do a lot of work to deliver 28hz so the the amplifier has to be able to make up for that. Basic physics....

Good news is Totem is one of the best at getting a lot of very good quality extended sound out of a smaller box (if you provide a suitable amp)  so you have a winner there no matter what.

I had a few friends own the Forest Sig and the Hawk, and while terrific speakers, neither puts out meaningful deep bass out into the room at volume...they probably put out 28hz at  - 3 or 6 db, at low volume a foot away from the driver...

I have the Forest Signatures in a 25 x 25 x 8 ft room. Running full range from Rowland monos with a single sub rolled off at the lowest point available and they are sublime. Which is to say they kick ass. Get a sub and enjoy life. They are fine speakers.

And how much music is really down in the 30 Hz? 
Some experience with live sound suggests less than we think.But I really like my speakers that can hit 20Hz, margin for the music that gets close.