Develop on Android Or Windows Store?

I want to develop a tablet app on PC with a Unity pro license so I need to use one of these options.

Do i…

Buy a Win RT tablet and use the Win8 pro license I get free with Unity Pro- £300
Buy an Android Pro license and develop on my current Android tablet- £800

Clearly the Win 8 option seems the best.

However, I guess the question really is…is there any disadvantage to developing for Windows RT? Is it as complete as Unity Android? I did read that I need to use Visual studio instead of Mono. Any other issues I should know before investing in a windows tablet?

Depends on your target audience. There is a much larger user base with Android so your app will have a broader audience.