This is my first post, and I hope you can help me to understand what's the best solution to our problem.
I'm not a developer, but I have good experience in web design.

We have a .net site about sport events with special stats and remote score submission features, these customs sections were created by developers.
They created also a custom CMS and custom graphics.
Other pages are usual website pages: About us, Gallery, Contact, etc.

The admin panel is very limited, quite raw, and often unreliable with no skins system for changing appearance.

But we absolutely need to have full control of appearance and graphics.

Since we plan to add soon new features to the site (more events, social network, e-commerce) we are at crossroad.

As it is, the existing .net site has too much appearance restrictions , we need to separate UI and graphics from implementation, and we need an easier and more effective admin panel.

We'd need something like WordPress dashboard and graphics capabilities (themes), with the power of .net.

Any suggestion?

Better to stay with .net or move toward PHP?

If we stay with .net, could it be a viable solution to adopt the skins system and some of its's best CMS available (DotNetNuke, Sitefinity; Umbraco, Mojo Portal, etc.)?

And what about integrating in some way in WordPress existing custom scripts for the sport activity management and stats?
I've heard good things about PHP compiler and .net WP plugin.

Please bring me the...light.

Thanks in advance for your precious help!!