Do no flange low profile shower bases present an increased chance of leaking?

If you look at the installation instruction for the base you linked (instructions linked right from the link you provided: instruction pdf), you will see on page 6:

Attach tile flange # 790112 (not included).

Follow instructions included with the tile flange.

So a simple web search for Duravit 790112 will lead you to a variety of vendors where you can purchase the flange that is required to be installed with this particular base for tiling.

It would seem that it would be best to follow the manufacturer's recommendation. If you are not comfortable with attaching the flange yourself, hire someone to do the install and get a warranty from them, or choose a shower base with pre-installed flange.

The reason the base does not have a pre-installed flange is so it can be installed in a variety of scenarios with either 2 or 3 tiled walls, glass or shower curtain, etc.