I own a Yamaha RD400 street bike from 1977.
The weakest link on all those 2strokers such as the Kawasaki H1 amd H2(widow Maker), the Suzuki GT(Water Buffalo) and Honda NSR was the lame ingition, (points and condenser).
Back in 1999, I bought a modern Electronic Ignition made by one of the RD forum's member from India. It would retard and advance the ignition by customizing your own curve, impressive spark and batteryless, that was cool.
There is no old or modern 4stroker 400cc streetbike that will get near me. I usually ride next to the 600's and 750's with no problem at all. Forget about the bigger and heavier cruisers.
If given the chance to build a 2 stroker mill with all the time and money just like the big automobile corporations have for the valves, I am more than certain they will build an engine that would outperform the 4stroker by simplicity, weight, space, economy and performance. There are few engineers and aficionados that have done it already.
Again, given same size engines (cc's), one a 2stroker, the other one a valve, with modern technology on them, please read http://www.hirth-motoren.de/en/2-stroke-logic.html
will definite outperform the 4stroker. There is no doubt!