Need some help with the Nokia N97 mini

Smartphone owners are no better than computer owners when it comes to endless arguments. The iPhone vs Blackberry battle is at least as fierce as the Mac vs PC one. For the last few years, I was definitely a Blackberry girl. I've never even considered buying an iPhone. What's more: I converted my boyfriend with the telling internet handle ApplefanBE to get a Blackberry, too. What I liked better in the Blackberry over the iPhone was

1. The keyboard. Many male iPhone users find that their fingers are too big for a touchscreen; and female users with long fingernails have iPhone touchscreen issues too.
2. Blackberry internet service, especially the push e-mail and over the air syncing with a Microsoft Exchange server: it just works. All the time. I never have to think about getting connected with the Blackberry. The only thing I have to be really careful about is not to use data roaming when I'm abroad.

But last week an unexpected present fell into my lap: a shiny new N97 mini. I really like the feel of this device. It has a touchscreen and a very, very decent keyboard. But here comes my problem: if I'm going to use this device for Exchange, POP3 and Gmail, for Twittering and Twitpicking, and for the occasional mobile browsing, what subscription should I use? I want to keep my mobile phone number, even worse: I want two SIM cards for the same number. One sits in the Blackberry, one in the N97. What should I choose? Proximus, Cherry, or MobileVikings?