I tried another component that I won't name that had so many steps before checkout that most potential customers just gave up... choose file, sorry you must login, where is the login?, where is the product again?, check the cart, add to cart, fill in your details, go to checkout, pay, where is the download link? Phew, hard work!
With document seller your customers don't even need to login they just choose the file, fill in their details, pay then have several options to instantly download the file... easy!
As an added bonus, Tuan gives the best support I have ever experienced for a paid component.
Highly recommended and worth every cent!
Also, the drag and drop menu where you can nest the form sections within containers and sections giving complete control over the form layout is genius.
There is a slight learning curve but if you take the time to view the video tutorial you'll make a great looking form in no time at all.
The in-built templates look great also.
Overall, a really great extension and I highly recommend it.