I like your idea of a complete rewrite for 1.5. One of it's current downfalls is that business logic is mixed up with presentation and database calls.

Your MVC OOP approach will take care of that issue. I would be willing to help with the devlopent.

My biggest piece of advice is not to recreate the wheel. Use a framework. Not only will that speed up development but you can we can get an instant base of users coming from the framework user base.

I highly recommend CodeIgnitor because it is easy and it is loosely coupled like Zend but without the obscure boxed way of coding. It als has a very small footprint and will work side by side with Expression Engines upcoming CMS.

I also highly suggest a module separation type of file organization. This would still be normal mvc but each part of the app such as projects, timesheet, reports will have a seperate folder that contains it's models, views and controllers. It keeps things nice and neat.

If you are interested in this type of approach, or just to discuss it, I would be very interested in coming on board because I was planning on something similiar already. Check out codeignitor.com. Either way I am interested int he future of this project.