The only real advantage these days is that they weight of the freewheel is more centered on the bike. They used to be used simply because in order to use small sprokets the freewheel had to go at the front. A 12 or 13t freewheel did not exist. These days with the invention of cassette hubs such as profiles the engagemtn system can be kept at the rear of the bike, which is arguably better because there is more room for the components to be larger and stronger. Alot of people these days go for a cassette hub but there are some people who still swear by a front freewheel. Some freewheels will not last long, ones such as Dicta's or ACS. If you definatly want a freewheel I'd go for the ENO freewheel, but if youd rather have a cassette hub go for something like a profile.