thnx for all replies.
KN : these are not for me ,for a friend .will use them on a boston-whaler-type boat.
as I understood no one likes omc's 2 much.but however they have the best service in my country.very well organised with a price list ,all necessary special tools ,computers etc.
Mercury is the weakest one.they dont have anything.hand made special tools-no computer-individual price lists(lol) .plus you have to wait for spare parts.
yamaha: this is also amazing story .believe it or not but I still have small outboard from 70's .it still works!! no service -no nothing-regular gas-felt down many times-went underwater.....
unbelieveable things happened to that engine but still working.if the bigger engines are like this ,it would be perfect...
so the final idea I get from this tread is:
if weight and speed is not important as long-engine life : yamaha is what I am looking for.
but will check their service before the order
thank you all for sharing your ideas and your help