The ng-forward approach is done with Angular 1.x dependencies and a few small helper libraries. ng-forward allows developers to use Angular 2 style TypeScript (annotations/decorators) without Angular 2. Unfortunately templates are still mostly in Angular 1.x style.
Once an application is converted to ng-forward style it is very close to Angular 2, but still requires refactoring. In most cases, ng-forward is not as efficient as ng-upgrade with respect to refactoring time. The payload of an ng-forwarded application is smaller, and porting to ng-forward can be done in an even more ad-hoc fashion than with ng-upgrade.
The general flow of ng-forwarding an application is:
- install ng-forward dependencies
- bootstrap root component
- upgrade components strategically
- refactor the codebase to Angular 2