Jason Wood has a great post regarding the recently filed NetSuite S-1 and their potential IPO: NetSuite IPO...another SAAS horseman braves the public markets.
The following quote gave me pause:
Does the fact that NetSuite is 7x smaller than SfDC indicate demand for back-office SaaS pales in comparison to front-office SaaS? In aggregate, back-office ERP is several orders of magnitude larger than front-office SFA, yet uptake of SaaS appears far less pervasive.
Aria has been toiling away at "back office SAAS" and it is inherently more difficult to implement than "front-office SFA" largely because of sticky issues like configuration, security and compliance. As an example it's hard to create a sandbox environment for our customers to create end-to-end testing because of necessary integrations with financial processors etc.
NetSuite has an additional layer of risk because they "touch the money," while SFDC, RightNow et al don't directly impact their clients' financial statements. (SAS70.....grrrr)
That being said, I do believe that "back office SAAS" is the next front in the SAAS vs. ISV battle.