Developing Cmdlets entirely in PowerShell is a best practice or not?

I'm developing an application for permission management purposes in applications such as Tfs, SharePoint, Project Server, Reporting Services and so on.

Administrators who will use this, will have several Cmdlets to do their routines.

I've at least two options:

1- Develop Cmdlets entirely in PowerShell.

2- Develop Cmdlets in C# .NET assemblies and expose them as PowerShell Cmdlets.

I prefer second approach, because of its easier development life-cycle, it has better source controller integration, better debugging, OOP, generics and so on.

But I'd like to know, what's a best practices ?