Personally, I think Drupal is very well aligned for this sort of application, and it has been done many times. (I'm an ex-Drupaler).
I think you'll find there will be alot of work involved making Silverstripe do what I think you want it to do. Far more than using Drupal anyway. I remember alot of community modules for building such a site.
Not really a failing of Silverstripe, you could pretty much use it, and Sapphire, to create anything you want. It just so happens that Drupal has already had alot of work done in this area that will get you rolling alot faster.
If you were to ask which would be more suitable for building information based sites, well, that would be the reason why I'm an ex-Drupaler. ;-)