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

Good question!

28-32hz - you might be able to feel rather than hear the bass in that range a bit more if a) its in the recording b) the rest of your system has good response down to below 28hz and c) the room acoustics support it, but probably a very marginal difference that may be hard to determine at best.

Many instruments can produce sound in that range, including synthesizer, tuba, bassoon, harp, organ, and piano.

So even if in the recording to start with, speaker response low enough to reproduce it alone does not mean you will hear it.

You can always run test tones through your system and see what happens.

Totem’s specs say "in room" meaning that 28hz (listed as 30hz on another "spec sheet" near the manual download page) rating requires reinforcement from room boundaries. Every speaker I’ve owned over the last several years have been positioned away from walls to lesson the room boom effect to some degree, and I suggest using a test CD (I have a few of the Stereophile test CDs and they’re great) to see actually how low these things go. My guess is even though Totems are cool well made speakers (Forest Signatures seem very nice), they’re never going to produce much at 28hz without a room doing some of the heavy lifting...that’s sub territory.

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...