Cracking situation to be in but I am looking at purchasing twin 250's for our chase boat for work. I have been using evinrudes for the past few years (all be it smaller models up to 115) and have been really pleased with them, however I have always liked the look of the Yams.
The evinrudes returned great reliability and economy however we did have a few issues with the evinrudes that were expensive to repair due to the specific nature of the injectors.
Personally I am a firm believer of who is able to offer you good service and warrenty will probably win out as both manufacturers are great.
Any views would be welcome to help me make up my mind.