I see a little confusion in the numbers here.........
I'll see if I can add to it.

First off I don't even know if that 3.4grs for every 1fps loss will hold true for a 70# or a higher draw length.........remember we were using a 28/61# bow for the example so the actual efficiency might vary. However if I were to guess HOW it would vary, I would guess that it will be even MORE effecient, based upon the bow being designed around a 30" platform.

Common sense would lead me to believe that if a bow at 28"/60# could do 237fps at 536gs, that if you took that same bow and added 2" of draw length to it, chances are you have a bow that is doing about 257fps +/- (if we all agree that 1" draw length generally means 10fps+/-) After all the starting point for the 28"/61# Allegiance was 306fps? 306fps is basically a 20fps drop over the IBO listed speed.

Now if you take that same bow that is doing (for sake of argument) 257fps at 30"/61# and a 536gr arrow, increase arrow weight by 14grains to 550(14gr/ 3.4= 4fps),......this should result in a net speed of about 253fps.
Now keep everything the same but bump the draw weight up 9-10#, and I find it very possible that a 30"/70# model could easily do 260+ with a 550gr arrow. After all the 30"/60# should only be about 6-8fps under 260fps.

I do have an “Armchair Engineer” theory WHY this thing is so efficient, and it has to do with the shape of that draw force curve.......it doesn't seem to slide up to a peak weight, it is basically at or near peak weight from the get-go (hence the comment that it “feels like a recurve”, and “it is stout right up front” ). This gives it more "front end drive" (for lack of a better term) which would be more necessary in powering a heavy arrow than a light one.
Where a regular bell shaped draw force curve actually loses weight/performance on the return cycle peaking somewhere toward the middle, this Equalizer cam carries it across almost to the point of rest givin’ this puppy one heck of a shove.

I didn't engineer the thing , but that is my impression of the nuts and bolts of why I think we are seeing some of these numbers with heavy arrows.
I am also starting to see in little snips of these reported numbers that this cam system probably isn't going to conform to our notions of "Standards" with respect to arrow weight/ velocity that we've grown accustomed to over the years.
This is a different animal that's for sure.

The thing I really find AMAZING in all of this is that I am hearing comments that it is as quiet as a Liberty and maybe just as recoil free.
Can you even imagine?