This is a question of particular interest to me. Personally I'm not a proponent of the commercially available frameworks. Some questions to bear in mind when you are evaluating for your use though are;

1) The scope of your development team, and of your project. If you have the time and development resources (Skill Sets and Personnel) You may well find the commercial frameworks inhibiting. However, the time to develop your own toolset may not exist.

2) How many other people may have to support what you've created? This may dictate your solution as well. If you have a large (use your own definition of large) development team, it may be less traumatic to get your team up to speed with a framework.

We are currently evaluating frameworks to provide a commonality of function department wide. One of our critical criteria is the ability to add enterprise specific business and presentation objects to the framework.

I have Toolbar and Error classes I would be happy to share if you are interested.

Regards,

Jason Tryon