I have a 91 190e 5 speed that took the longest of any stick to figure out how to shift smoothly. My feeling is almost all of shifting smoothly is throttle control, engine response including weight of the flywheel and the type of fuel system. My motorcycle has the carbs right on the head and almost no flywheel. I have to run through the whole shift sequence real fast to get a smooth shift. My Peugeot diesel has real good response but a heavy flywheel. My wife's got good response with multiport fuel injection, (injectors pointed at the intake valves). But the Mercedes has doggy response for shifting with its fuel distributor at the end of mile long fuel lines. With my variety of experience on different throttle-engine-clutch response machines I've made the Mercedes shift like silk, but if I'm off just a little bit there is lots of clunking. Another factor in engine response is the loading of the air conditioning compressor (its a real surprise when it switches mid-shift). Of course being an engineer helps figuring all this out.
But my real feeling is that you all should wait for the great Larry Bible to show his head on-line.
5 speed '91 190E 2.6 320,000 mi. (new car, fast, smooth as silk six, couldn't find any more Peugeots)
5 speed '85 Peugeot 505 2.5l Turbo Diesel 266,000 mi. (old car, fast for a diesel, had 2 others)
5 speed '01 Jetta V6 (new wifes car, pretty quick)
5 speed '85 Peugeot 505 2.2l Turbo Gas 197,000 mi. (wifes car, faster, sadly gone just short of 200k )
5 speed '83 Yamaha 750 Maxim 14,000 mi. (fastest)
0 speed 4' x 8' 1800 lb Harbor Freight utility trailer (only as fast as what's pulling it)