Let me ask a question which betrays a bit of my ignorance about variable valve timing schemes. I would describe the S2000 VTEC approach as 'digital': above 6000 rpm, there is an electronically controlled lock up of a second cam follower, and suddenly the high lift cam takes control. I presume that is the reason that you can feel a distinct step in acceleration and engine noise as VTEC suddenly takes hold.
Now, BMW also uses variable valve timing, but I believe it is hydraulically controlled and progressive. My understanding is that the camshaft's timing and/or lift profile changes steadily over a transitional rpm range. I even recall hearing that as a result, the variable valve timing mechanism can wear out or become erratic in high mileage Bimmers.
I know that out VW Passat V6 also uses some sort of variable valve timing scheme. I don't know anything about its technical characteristics, but there is no noticeable transition effect anywhere in the rpm range. This makes me suspect that the method is also mechanical and progressive.
My guess is that the Honda approach is the most reliable, because there is less complicated additional machinery to wear out - only an electronic control system, and we all know that electronics never fails!!
Wrench-heads of this forum, can you enlighten me further? My feelings will not be hurt if I have been in error in anything I have said.

 

The Honda Vtec is probably better called a variable valve lift, of which there are two positions available, high and low. It is switch electronically via a solonoid/spool valve, but that actually allows oil pressure to push a pin in the valve rockers which locks them together, and forces the use of specific lobes.

Variable valve timing in the BMWs (Vanos), allows for the advance or retard of the cam timing in realtion to the crankshaft postion, but does not change lift characteristics. This is why you don't feel the power change as in the Hondas.

BMW has a new wacky system now which will have variable everything, best of all worlds. Really neat stuff.

 

The new toyota Celica GT-S has variable timing and lift. And when that large cam comes on, you can feel the additional 20+ hp jump.