Cleanliness of a belt drive, efficiency of a chain drive

BioLogic FreeDrive

it’s a really nice design but i think they only have this on the 2010 dahon uno model and nothing else. Plus I think this can only go on internal gear hubs and single speeders only. But overall it’s a great desgin, I think I saw this chain cover on the web somewhere that they sell. Ah wait here’s the site:

oh yeah it’s nice when the chain is in good weather but from the dahon site some are saying it’s a dirt and water trap, which doesn’t quite trump the versatility of a exposed belt that can be hosed and dried off without messing around with the cover when it needs cleaning. … entry60798

There was a craze for these plastic chain tubes in the 80s/90s for BMX and kids Bikes, but it soon died out. It’s a good, intermediate step for Dahon - to add a $1 plastic pipe to a chain drive to be able to claim many sales advantages of a belt drive, and MUCH Cheaper. They soon died out on kids bikes because they soon fell off or got damaged - but maybe adults are more carefully and they will last a bit longer on folding bikes.

For two months I have Dahon Bullhead with this solution. It is good idea, but can’t be treated as replacement for belt. Chain is protected against dust and mood and what is more important it really protect hands and legs against most of grease grom chain. But as I wrote, it is not so clean as belt and doesn’t replace it. Strida with belt and disc/roller brakes look to be cleanest bicycle.
Talking about efficiency comparison is not easy becouse this solution I use on bikes used for other distances and in other way.
Better is that more standard components can be used: chain, sprockets, gear hub etc…