Since I've never used a shavette, my input falls into the category of guesswork as opposed to educated opinion. However, despite the fact that the razor itself seems to be the only independent variable, I would bet there is something different about your technique when you switch from one to the other. Having used a DE for so long, you're undoubtedly more comfortable with a disposable blade than the fine precision tool we call a straight razor. Are you applying the same pressure (should be very light) with both razors? Do you find the longer straight blade more cumbersome than the relatively small blade in the shavette? Do you find you are more anxious holding the Dovo? Small things like these can subtley influency your habits without you realising it. I'm also wondering about your stropping. Did you strop the razor before your first shave? If so, that is probably the culprit.