OSC 2.3.1 is propably one of the last releases of "old " osc and the new one with completly new framwork is going to be stable (currently 3.0.2) - have you plans to develop MarvikShop with OSC 3.X and the next LTS release of Joomla too?
The main goal was to use Oscommerce as a component on the latest Joomla. So you can use all the benefits of Joomla. Especially the templates and the use of more components. Also we use the same database tables and Easy Populate to copy you old Oscommerce site to MarvikShop.
For the moment we have no plans to use OSC 3x. Because several solutions where solved by Joomla itself. But we use all the bugfixes we can find from:
Osc max etc.
And of course with the help of the users from MarvikShop.
MarvikShop should be use in the next LTS release. It works perfectly on Joomla 1.7.2. (Hopefully the don't restyle the registration process again;) ) And we try to install always the latest version of Oscommerce add-ons.