I would neither go for XPages nor for Flex but doing a testdrive with JBoss SEAM.
There are many advantages of this choice:
All of it is free.
You get a very nice IDE.
You can use all your knowledge of web development.
You can get a very quick start using seamgen and many examples.
You can make use of a large developer community including some of the best java developers in universe.
Although the whole thing is very complex you can build complete JEE apps very fast.
During many years of being a Domino Developer I never liked web development with Notes very much. But using Seam and the JBoss Developer Studio it is really fun. You even can use Flex in combination with Seam if you like.
I would neither go for XPages nor for Flex but doing a testdrive with JBoss SEAM.
There are many advantages of this choice:
All of it is free.
You get a very nice IDE.
You can use all your knowledge of web development.
You can get a very quick start using seamgen and many examples.
You can make use of a large developer community including some of the best java developers in universe.
Although the whole thing is very complex you can build complete JEE apps very fast.
During many years of being a Domino Developer I never liked web development with Notes very much. But using Seam and the JBoss Developer Studio it is really fun. You even can use Flex in combination with Seam if you like.