The product is mature and...

jeckCA, USA5 stella
The product is mature and solid, so I didn't have to refer to help or support all that much, however. Having used the product for about 7 years (first in .NET 1.1, recently in 3.5) I consider SF components almost an extension of native controls, sort of like WinForms/WPF Professional :) It's hard to go back to just native UI toolbox. Quick responses from support show the professionalism of Syncfusion guys. As soon as you open a ticket they give you a date (usually next day) by which you will receive the response. The response most of the time will have a sample ready-to-run project with the fix.