Looking at the graph with the Broadband DSP and the M80v3 I looks to improve bottom end to the same point as the M80v4.
Actually, the graph looks to be better than the m80v4.

I am wondering if it be better to purchase the DSP at $750 than upgrading at a cost of $1100 ?

Also, just wondering if this DSP goes inline inbetween my Reciever and my external amp. There are no pics of the rear. Not sure how it connects

If the DSP is the same as mine for the LFR speakers, then yes it fits between the Pre-Amp and the Amp. I would expect that you can order it in different levels (in RCA or XLR connectors).

Now speaking with Brent .. i believe that Axiom is working on some new units. I know they have newer designs for the LFR units, but I don't know if that will effect the other DSP units.

OK, Called Brent today and he explained