@DeathByVisualStudio: There are potential non-technical side of problem for having Apps in multiple platform.
Having In-App purchase regulation in iOS (section 11) and WP (section 5e) at the same time effectively make "I want to build App for both platform, and make features bought in any of the platform automatically switched on too when login in App of other platform with same account" breach of contract. App developer have to choose to:
1) sell the App as a whole;
2) seperate user accounts for different platform;
3) App builders who want to use micropayment strategy just choose the platform with bigger marketshare.
Now spare me some time while I curse whoever make such bureaucratic roadblock...
Valid points but I would hope that you could abstract much of that out. That may mean you have a ridiculously complex build process but once setup it shouldn't be too bad.