(Caveat: I have absolutely no inside information about the strategic plans of either NetSuite or Adaptive Planning)

This seems to be an acquisition that makes sense.  I know they have only been partners for a couple of months but why wait?    They could continue a nice comfortable partnership but my advice would be to take the plunge and tie the knot now (note: this advice comes from a man who didn't get married until he was 40).

Why Not Wait?
Why am I pushing a quick marriage on these two SaaS vendors? 

1. Their combined SaaS story is more powerful together than individually.
2. On-premise ERP vendors have successfully jumped headfirst into the BI and PM market through acquisition, SaaS ERP vendors would benefit form following suit.
3. It would expand their combined revenue opportunity just as it has for the on-premise vendors.
4. The combination provides a breadth of SaaS solutions that would increase the credibility and viability of the SaaS alternative to on-premise financial applications.
5. The publicity will generate market awareness that will benefit the combined entity and the overall SaaS market.

Beware of "The Seinfeld Effect" of Partnering
The reason for vendor partnerships prior to acquisition is usually to test the market for the combined product lines, determine integration strategies and expose any underlying issues with the partners' product lines.

Those of us who watched Seinfeld incessantly remember how notorious he was for finding some inane fault with every woman he ever dated on the show. 

Jerry could always find some "flaw' in any person that would eventually sabotage the success of every one of his relationships.  This can happen in software vendor partnerships as well.    All software has "warts" but some can be removed and some need to be overlooked.  Sometimes partnerships lack the commitment to overcome the barriers that need to be addressed and work around those that cannot.  An acquisition creates that "for better or worse", no finger pointing, commitment to make it work that prospects want from their vendor.

So, NetSuite and Adaptive Planning, take the plunge - make the commitment.  You know you both want to.  Do it for yourself, do it for the SaaS market, do it for your investors.  Work out a nice prenup and get on with it!