At the risk of sounding like one with pointy hair, I just can't imagine a company making an informed decision to use Subversion on Demand compared with other commercial alternatives.
I am every bit the open-source zealot - I shit you not, I'm wearing a GNU baseball cap right now - but even I would not choose Subversion over, for example, Perforce.
See: http://www.perforce.com/perforce/price.html
For an organization with only 20 users, your talking about an extra 11$ per month per user for a more stable, better supported system.
In my experience, perforce outperforms subversion in every way, especially stability and scalability (though neither is particularly scaleable). Pretty much the only advantage of subversion is that it is open and non-proprietary.
Now take an organization with over 100 users - your actually paying the same for Perforce versus Subversion. In my mind, this is a no-brainer. If CollabNet wishes this to be successful, they might want to rethink their pricing (yes, I realize that the cost of hosting is figured in there too, but the cost to buy a machine and set up on the local network for the perforce case is amortized).