I used to downshift to slow down but when I started getting professional training in high perforance driving with the Skip Barber Racing School I as told that that is not a good technique. They stressed that the brakes are for slowing the car down and the transmission is for getting the car in the proper gear.
Now when I am driving an MT I will use the brakes to slow the car and will heel and toe downshift and double clutch through the gears as the car slows to a point where I need to be in a lower gear. After driving that way for years it became second nature. Double clutching is totally unnecessary in a car with a fully synchomeshed transmission but I do it because I like to and becuase it keeps me in practice for the track car. The only time I use engine braking is when I am descending a long steep hill.
Coasting in neutral is never a good idea.
Drivers Club at Lime Rock - International Motorsports Research Center
Madison Avenue Sports Car Driving and Chowder Society (Only a Vice President)
Polish Racing Drivers of America (PRDA)
The Glen Club - Sports Car Club of America