[noeffred]

Let's shed some light on this:
Pro drivers do not necessarily have a rougher frequency response than their Hi-Fi counterparts, although many do. They usually are more efficient because in the pro field, every single watt counts. Also, they are quite robustly built and can usually deal with quite a lot of punishment before taking serious damage.
They are work horses, tools so to speak. Many offer excellent sound, but, primarily, they are conceived to be efficient and robust. Also, they can be quite ugly whereas a Hi-Fi driver usually has a more living room friendly look.

In general, you can't say, that the hifi drivers offer better sound than their pro counterparts, as there are equally many rotten apples on each side of the fence.

There are some things you can only get from the pro sector. For instance huge bass drivers (18" upwards) are nothing uncommon, whereas I couldn't name such a big Hi-Fi driver.

You shouldn't see Hi-Fi and pro as separate classes, if you're looking into DIY. It really just depends on what features you're looking for in a driver. If it's high efficiency and robustness you're after, then a pro driver might be better suited for you.