We are ready in our company to move everything to Python instead of C#, we are a consulting company and we usually write small projects in C# we don't do huge projects and our work is more based on complex mathematical models not complex software structures. So we believe IronPython is a good platform for us because it provides standard GUI functionality on windows and access to all of .Net libraries. 
I know Ironpython studio is not complete, and in fact I had a hard time adding my references but I was wondering if someone could list some of the pros and cons of this migration for us, considering Python code is easier to read by our clients and we usually deliver a proof-of-concept prototype instead of a full-functional code, our clients usually go ahead and implement the application themselves
My company, Resolver Systems, develops what is probably the biggest application written in IronPython yet. (It's called Resolver One, and it's a Pythonic spreadsheet). We are also hosting the Ironclad project (to run CPython extensions under IronPython) and that is going well (we plan to release a beta of Resolver One & numpy soon).
The reason we chose IronPython was the .NET integration - our clients want 100% integration on Windows and the easiest way to do that right now is .NET. 
We design our GUI (without behaviour) in Visual Studio, compile it into a DLL and subclass it from IronPython to add behaviour.
We have found that IronPython is faster at some cases and slower at some others. However, the IronPython team is very responsive, whenever we report a regression they fix it and usually backport it to the bugfix release. If you worry about performance, you can always implement a critical part in C# (we haven't had to do that yet).
If you have experience with C#, then IronPython will be natural for you, and easier than C#, especially for prototypes.
Regarding IronPython studio, we don't use it. Each of us has his editor of choice (TextPad, Emacs, Vim & Wing), and everything works fine.
Pros and cons of IronPython and IronPython Studio