Flashbuilder4 with GAE thoughts

[ProjectedSurplus]

I want to build a highly scalable "facebook for business" and after much testing am pretty set on FlashBuilder4 (Flex) with Google App Engine (GAE).

What are the thoughts on the need/advisability of also using Spring/Cairngorm/etc frameworks? (Frankly I don't have extensive experience coding, however feel the "MVC utopia" universally aspired to becomes convoluting when duplicating between front and back ends as envisioned above  -- i.e. Flex/ActionScript and GAE/Java respectively).

Also, I am leaning toward GraniteDS (i.e. to facilitate AMF) rather than LiveCycle et al -- though I am quite enamored with the "data wizards" in FB4 which may make prototyping at least better in a completely Adobe environment ????

Thanks for any feed back/thoughts

[Greykid]

ive come to the same conclusion as you.  doing fb apps in as3 api also looking to use  graniteds amf and gae using  gas3. doing sample in eclipse j2ee  now but next step is graniteds. please contact me at robert@activecommunity.com to disscuss further. typing on my nexus1  w AIR and flas 10.1 installed