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?

Here what TAP is telling me. For arguments sake I'm using the top end number 323fps as well as 331fps (bare string +8fps).

@ 323fps
30" 60lbs 540gr = 250fps 75KE
30" 70lbs 540gr = 267fps 85KE

@331fps (bare string)
30" 60lbs 540gr = 256fps 79KE
30" 70lbs 540gr = 273fps 90KE

I have found TAP to be quite accurate w/in 1-3fps, take them for what they're worth. If you look at the low end. 315fps & 323fps (bare string).

@ 315fps
30" 60lbs 540gr = 244fps 71KE
30" 70lbs 540gr = 260fps 81KE

@ 323fps (bare string)
see above

I would say 260fps w/ 500gr+ arrow should be easily attainable in my opinion and if the cam is more efficient then these numbers could be higher.

These numbers are based on theoretics no actual testing will be done, hopefully next weekend I'll be doing some testing with my 30" 60lb Old Glory.

My interpretation of the efficiency of the Equalizer cam: As with most cams, the weight builds as you draw. The E cams are near peak at the front. Other cams will hit hard, initially, at release. Then deliver less energy as the cam rotates toward brace. The E cam will not hit quite as hard initially, but will continue to deliver more energy, as it returns to brace. If I'm right, this would account for the higher efficiency with heavier arrows. Possibly with shorter draw lengths as well.

The Old Glory I ordered will only be 50lb.limbs so I guess I will be checking out the lower end of the K.E. scale When they chrono the bow at the factory will it be at 5 grains/pound? I don't have any arrows less than 300 grains[8D]

Bowshopper,
Yes they will chrono the bow with a 250gr arrow.....but it doesn't sound like you will have too many probelms with your 300gr ones.