Everyone's different
TJ,
I still use Outlook for email and I still use the Outlook calendar. But on my desk sits my trusty iPad with Omnifocus at my fingertips. So if I need to refer to my task lists, I just swivel my chair and look at the iPad. If you're someone that is constantly turning an email into a task, you may not love OF on the iPad so much. But you might just do a 30-day free trial, play with it, and see what all the fuss is about.
One very cool feature: If you have a task and you need to print it out or send it to someone else (along with all the notes), you can email it from OF. For instance, I had a long list of things to buy at a store yesterday and all those things were in the notes field. I emailed it, printed it from my pc, and off I went. Sometimes I send my husband a list of stuff to pick up on the way home too (much better, right?)
If I were rich and had a huge amount of space in my office, I'd buy a Mac to go along with my PC just because of OF! But I'll never switch over to a Mac completely because of the investment I have in PC software and the learning curve to go "all Mac". If the OF people ever develop a product that works on PC's, LOOK OUT!
P.S. Thanks for the kind words about the podcasts. It's a great group of people and a lot of fun to participate--I just wish I could be on every call, like the old days. As for GTD Connect, I can't say enough about it! I think I've been a member for about 5 years now and I learn something new every week. Best money I have ever spent (I own my own business too, by the way).
Hope this helps. I'm happy to answer any other questions you have. I don't often look at the public forums and could miss something. Feel free to shoot me an email privately.