50% is not a stretch by any means, I work at a parts store and id say AT LEAST 50% of the calipers I sell are integral style, lots of companies use them such as, Honda/Acura, Volkswagen/Audi, BMW, Mercedes, Nissan etc etc.

I shouldn't have said "efficient", in reality because of heat complications disc brakes are more efficient, but what I meant to say and misspoke was that drum brakes are more effective at stopping.
And if you don't believe me about them being more effective, look it up. Drum brakes because they are capable of covering more surface area with friction material at a single point in time are in fact more effective, and as i stated earlier the only reason companies phased them out is because of the complications with cooling etc.
If you still don't believe me again I suggest doing some research on the matter, in a side by side match up for a one time emergency use, drum brakes will win out over disc brakes.