I think using your engine to slow down is not generally a great idea. More rev's = more wear no matter how you look at it. If you are talking Vintage Ferrari's from the 50's up to early 70's, then yes, if you are really hustling the car you will need engine braking to slow down... almost all cars from those years do... as brakes were not as strong... and really old cars using Drum Breaks dont slow well... however I do not know many people driving a 275GTB hard on the road, and when they do, clearly brakes are far cheaper and easier to replace than a gear box. On a race track in a 512 M or S, for example, you would want engine braking to help slow down and balance the car in the entry to a corner, more specifically you want to ensure that traction on the slowing wheels is not overloaded and locked up, but you also dont want brake bias to the rear for the same reasons. Driving a 250 SWB - like at Goodwood, they are using Engine braking to balance the car, as its slides.... This is not something that modern ( 1980's to 2000's ) Ferrari's do. Matching rev's in a 308 takes practice and skill, but when done well, works great, as its technically a 60's design. doing the same thing in a 550 or 360, takes a bit less skill, but also the reward just is not there, better to use the brakes, ensure you are in the right gear to exit a corner... and on the throttle. Modern F-1 cars - use engine braking to recover heat and excess energy... so its built into the software. Any good driving school will tell you brakes are for slowing gears are for accelerating... they have to be used in unison and complement each other.