Straight to your questions:
If you build the application using RadControls for ASP.NET AJAX you will achieve cross-browser support. But you should know that we still have issues with mobile devices which we are polishing out and the controls are not especially design to work on mobile browsers.
About the difference between the ASP.NET and Kendo controls:
- ASP.NET AJAX controls are server-side controls, made to work in Web Forms. They use ViewState, created on the server, following the Web Forms Page lifecycle. For some of the operations they require postbacks. The ASP.NET AJAX controls are adopting only these HTML5 features that work in all browsers we support.
These are a few of the differences. Which platform you choose is an architecture decision that you need to take depending on your target users, the resources and knowledge you have.
In addition, I suggest that you check this topic
and see if helps.
And it is also good to try them both and work with them for your proof of concept.
All the best,
the Telerik team
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