It's very difficult to find a solution on the market that incorporates all three tiers of development. The guys at Ideablade are very helpful and responded to my questions promptly.
One thing you should not under estimate is with every framework there is a learning curve but once experienced it can make an experienced developer a number of times more productive.
At this stage I'm not considering Silverlight but do agree the licensing for the BOS server needs more clarity. At the end of the day you don't want licensing to eat into your profit or price yourself out of the market but you need to compare it with the development of RIA and if you will save money on the long run.
I've decided to bite the bullet and give it a try, so I'm busy with the development of my product using IdeaBlade and ASP\WPF\Winform controls from DevExpress.
Creating the Data Access layer and business layer is very easy and initiative but would recommend that IdeaBlade develop better and more intuitive code generators for user interfaces. Another issue is the version supportability between DevForce and DevExpress. DevForce is always a couple of version behind DevExpress control release.
I will keep you posted with my progress.